Radiological Differential Diagnosis Satish K Bhargava
INDEX
×
Chapter Notes

Save Clear


Chest1

 
1.1 LESIONS OF THORACIC INLET
 
 
Anatomy of Thoracic Inlet
  • Thoracic inlet/root of neck is a narrow space that serves as a junction between the neck and the thorax.
  • Boundaries are
    Anteriorly:
    Manubrium
    Posteriorly:
    First thoracic vertebra.
    Laterally:
    First ribs.
  • This area is further delineated by Sibson's fascia which extends from the transverse process of C7 vertebra to the medial border of first rib.
  • Plane of the thoracic inlet, is tilted downward anteriorly and laterally on either side being highest medially and posteriorly (Fig. 1.1.1).
    2
zoom view
Fig. 1.1.1: Thoracic inlet as seen from above. Note presence of cervical ribs (gray area) on both sides. On right side of thorax, rib is almost complete and articulates anteriorly with first rib. On left side of thorax, rib is rudimentary but is continued forward as fibrous band that is attached to first costal cartilage. Note that cervical rib may exert pressure on lower trunk of brachial plexus and may kink subclavian artery.
 
Differential Diagnosis of Lesions at Thoracic Inlet
  1. Congenital lesions:
    Lymphangioma
    Hemangioma
    Cervical extension of mediastinal thymus
    Thymic cyst
    Vascular anomalies.
  2. Inflammatory lesions:
    Inflammatory adenopathy—TB, Mononucleosis, HIV infection, etc.
    Cervical abscess3
    Tubercular spondylitis with abscess
    Retropharyngeal abscess with mediastinal extension.
  3. Benign tumors:
    Lipoma
    Lipoblastoma
    Schwannomas and neurofibromas
    Fibromatosis.
  4. Malignant tumors:
    Lymphoma
    Neuroblastoma
    Thyroid carcinoma
    Pancoast tumor
    Lymph node metastasis
    Liposarcoma
    Metastasis to thoracic vertebra and ribs.
  5. Traumatic lesions:
    Pneumomediastinum
    Esophageal foreign body
    Cervicothoracic hematoma
  6. Miscellaneous:
    Cervical rib
    • Thoracic outlet syndrome
    • Intrathoracic goiter.
 
Lymphangioma
Develops from congenital obstruction of lymphatic drainage.
Tends to surround and invade normal anatomical structures. Five percent occur in neck (posttriangle); 3–10% extend into mediastinum, asymptomatic and painless masses, 90% detected by 2 yrs of age.
Imaging: Multilocular transseptal masses of fluid attenuation, walls of septa-enhance (if history of surgery/infection). 4Occasionally hemorrhagic areas and fluid-fluid levels are present.
 
Hemangiomas
Benign masses composed of proliferating endothelial cells characteristically increase in size and gradually involute. Most commonly occurs in 1st year of life.
Imaging: Calcified phleboliths within mass may be present. Enhance with adjacent vascular structure and fill with contrast over a short time.
MRI: Intermediate SI on T1WI and high SI on T2WI, fatty replacement may be present.
 
Cervical Extension of Mediastinal Thymus
  • Due to incomplete mediastinal descent and manifests as solid midline thymus at thoracic inlet.
  • Diagnosis is made on the basis of homogenous SI similar to that of the thymus with all MR imaging sequences or connection to the normally located thymus.
 
Thymic Cyst
  • Caused by persistence or degeneration of the thymopha-ryngeal ducts.
  • 50% of cervical thymic cysts are continuous with medi-astinal masses. Most commonly on left side.
CT: Well marginated, unilocular/multilocular, attenuation is close to water.
MR: Decrease SI on T1WI and intermediate/high SI on T2WI.
SI on T1WI may increase if cyst contains blood/protein.5
Then septa may be present.
When these cysts occur in neck they are located partially within the carotid sheath.
Most thymic cysts are congenital but they have also been reported with infection, neoplasms, radiation therapy, trauma and thoracotomy.
 
Vascular Anomalies
  • Venous malformations and AVM are rarely seen in neck.
  • Jugular vein thrombosis occurs after placement of a central catheter or in association with compressive lesion and is seen as luminal obstruction with thin rim of enhancement of the vasa vassorum.
  • Cervical aortic arch—High positioned, usually right sided aortic arch. Occasionally associated with other cardiac and vascular anomalies, patient presents with respiratory problems/dysphagia.
    A pulsatile mass is found in the neck.
 
Cervical Abscess
  • Cervical abscess seldom cross the thoracic inlet into the mediastinum.
  • Infection in the visceral space may extend into the anterior mediastinum, whereas infection in the retropharyngeal and prevertebral spaces may extend into the posterior mediastinum.
Imaging is required to distinguish cellulitis and suppuration adenopathy from abscess which require surgical treatment.
In suppuration-focal hypoattenuating mass with an enhancing rim on CECT and a complete hypoechoic to anechoic mass with a variable thick rim of solid tissue is seen on ultrasound scans.6
In fluid collection-SI on MR varies according to protein content, skin thickening and reticulated fat planes may be seen adjacent to the abscess margins in CT and MR.
 
Tuberculous Spondylitis with Abscess Formation
  • Infection usually starts anteriorly in the vertebral body.
    In 90% cases at least 2 vertebra are affected.
    Skip lesions occur in 4% cases.
    Paraspinal abscess are present in 55–90% cases.
    Imaging features:
    • Vertebral body destruction.
    • Loss of disc space.
    • Paraspinal abscess
    • Prevertebral and epidural collections.
    • Paraspinal calcification.
    In neck—dysphagia, hoarseness and lymphadenopathy are accompanying features.
 
Retropharyngeal Abscess with Mediastinal Extension
 
Causes of Retropharyngeal Abscess
  • Tonsillar infection
  • Iatrogenic/traumatic
  • Perforation of pharynx.
X-ray neck soft tissue: Retropharyngeal soft tissue thickening, Forward displacement of airway.
CT/MR: Retropharyngeal collection continuing into the post- mediastinum through the thoracic inlet.
 
Lipoma
  • Most common cervical neoplasms of mesenchymal origin.
  • Typically present as painless slowly growing masses, most commonly occurring in posterior triangle.
    7
CT: Homogenous nonenhancing mass, isodense with subcutaneous fat, usually well-encapsulated lesions. (−10 to −100 HU).
MRI: SI similar to subcutaneous fat (increase on T1WI, intermediate SI on T2WI and loss of SI on fat suppressed MR images).
 
Lipoblastoma
Rare, usually encapsulated benign neoplasm of the embryonal fat. Composed of mature and immature fat and found almost exclusively in infants (90% <3 yrs) and children.
Most common site—Extremities → trunk → head → neck.
CT: Fat separated by septa of soft tissue which does not enhance.
MR: Heterogenous and have intermediate to high SI on T1WI according to the amount of immature fat. On fat suppressed images-areas of high SI is suggestive lipoblastoma.
 
Schwannomas and Neurofibromas
Common sites are—vagus nerve, ventral and cervical nerve roots, cervical sympathetic chains and brachial plexus.
Plexiform neurofibromas are pathognomic of Type I neurofibromatosis.
CT: Hypo to isoattenuating at CT. Contrast enhancement is more often seen with schwannomas.
MR: Low to intermediate SI on T1WI and intermediate to high SI on T2WI. Shows nonuniform enhancement. Plexiform neurofibromas usually involves cartilaginous soft tissue.8
Malignant degeneration is seen in 15–30% cases.
Tumor arising in vagus nerve—displace the common carotid and internal carotid arteries. Anteromedially and the internal jugular vein posterolaterally.
Sympathetic chain tumors demonstrate a constant relationship with the longus colli muscle.
Brachial plexus tumors displace the anterior scalene muscle anteriorly.
 
Aggressive Fibromatosis
Characterized by proliferation of fibrous tissue with locally aggressive behavior and a tendency toward recurrence after resection.
Etiology is unknown.
Appearance on MR is often infiltrative and can suggest malignancy. Usually has decrease SI on T1 and T2WI which permits diagnosis.
 
Lymphoma
  • Hodgkin's disease accounts for majority of lymphomatous anterior mediastinal masses and the neoplastic cells typically infiltrate the thymus.
  • Thymic involvement is always accompanied by involve-ment of mediastinal lymph node.
  • Lymphoma of neck involves cervical lymph node chain, Waldeyer's tonsillar ring and lymphoid tissue at the base of tongue. Such lymphoma is most often of the non-Hodgkin's type.
  • Calcification and necrosis can be seen if lymphoma was treated previously.
    9
 
Thyroid Carcinoma
  • Papillary carcinoma accounts for 75–90% of all cases and is especially prevalent in younger patients.
  • Medullary, follicular and anaplastic carcinoma accounts for 10–25%.
  • Usually evaluated by ultrasound or scintigraphy. CT/MR is required to evaluate tumoral extent when malignant tumors are suspected.
  • Difficult to distinguish benign from malignant nodule because the findings are nonspecific, however thyroid masses with infiltrating margins that obscure soft tissue plane and associated with adenopathy is suggestive of carcinoma.
  • Cold’ nodules on scintigraphy have a higher frequency of malignancy.
  • MR is preferred as compared to CT because iodine administered during CT can cause iodine 131 therapy to be postponed for upto 6 months after removal of maximum tumor volume.
 
Neuroblastoma
  • 10–15% neuroblastomas are located in posterior media-stinum. More than 5% neuroblastomas arise in neck.
  • Arise from the renal cell rest blasts located in the adrenal gland or sympathetic chain.
  • Osteochondritis and ipsilateral Horner's syndrome is related to lesion of cervical sympathetic nerve.
    • 50% neuroblastoma show calcification on X-ray.
    • 90% show calcification on CT.
    • MR imaging is the modality of choice for demon-strating the full extent of mass, chest wall invasion and extra-adrenal intraspinal involvement.
      10
 
Metastatic Lymph Nodes
Head and neck squamous cell Ca
Renal cell Ca
Breast Ca.
Seminoma
Melanomas
Mucinous adeno Ca of GIT
Neuroblastomas
Nasopharyngeal Ca
Rhabdomyosarcomas
Thyroid Ca
Small cell Ca of lung
Ovarian and prostate Ca
Lymph nodes involved are deep cervical lymph node along internal jugular vein, supraclavicular lymph node, scalene nodes, highest lymph node in superior mediastinum.
 
Pancoast Tumor
  • Pancoast syndrome consists of a constillation of signs and symptoms that include shoulder and arm pain in the distribution of C8, T1 and T2 nerve roots, Horner's syndrome and atrophy of hand muscle.
  • This is caused by tumor in lung apex (Squamous cell carcinoma) which is causing invasion of the chest wall, and prevertebral sympathetic chain or the inferior or stellate ganglion.
  • A Pancoast tumor should be ruled out if—unilateral pleural thickening or asymmetric thickening. > 5mm is noted on chest X-ray.
Metastases: (to rib and thoracic vertebra).
Usually has a mixed pattern: Breast/lung.
Blastic—Prostate.
Lytic—Thyroid, kidney.
Vertebra—Pedicles and vertebral body is involved.
Ribs—Lesions early recognized when rib is expanded.11
 
Pneumomediastinum
Air can travel from the mediastinum along the fascial planes to the neck; subcutaneous tissue and chest wall.
Most common cause in children: are asthma, aspiration of foreign body, trauma.
Esophageal—foreign body granuloma.
  • Most commonly seen in infants and children.
  • Most common site of retention is the upper esophagus at the thoracic inlet.
  • Long standing foreign body produces a granulomatous tissue reaction that manifests as mass.
  • Mediastinites and abscess can be seen in this region as a complication of foreign body perforation.
 
Cervicothoracic Hematoma
 
Causes
Trauma
Faulty placement of central catheter.
Hematomas are usually transspatial lesion
 
CT
Hyperdense in acute phase
Hypodense in chronic phase
and on MR SI varies depending on the phase.
 
Cervical Rib
Seen in 1% of population.
Symptomatic in 10%
Unilateral in 50–80%
Cervical ribs vary in length and may be connected to the first rib by a fibrous band.12
Cervical rib may affect the brachial plexus in one of two ways.
  1. May narrow the space between the posterior aspect of 1st rib and anterior scalene muscle through which the nerve and subclavian artery passes.
    Or
  2. Cervical rib may be situated such that a portion of the brachial plexus must pass over it thereby stretching the lower trunks. Results in cervical rib syndrome—Sensory symptoms usually antedate motor involvement and occur along the ulnar border of forearm and hand.
    Muscle wasting of Thenar eminence.
 
Thoracic Outlet Syndrome
Because of compression of subclavian artery and C8/T1 nerve.
 
Usual Causes
  • Cervical rib
  • Elongated transverse process of C7.
  • Fibrous band extending from transverse process of C7 to first rib.
  • Low set shoulder gurdle.
  • Pancoast tumor.
 
Intrathoracic Goiter
Characterized
  • Continuity with cervical thyroid gland.
  • Marked enhancement on CECT
  • Well-defined margins
  • Inhomogenity
  • Focal calcification.
    13
zoom view
Flow Chart 1.1.1:
 
CYSTIC
 
Lymphangioma
Detected by 2 yrs of age, seen to extend from posterior triangle multilocular cystic mass.
 
Thymic Cyst
Unilocular/multilocular cystic mass seen in continuation with thymus.
 
Cervical Abscess
Hypodense collection with enhancing rim with adjacent reticulated fat plane.
 
Potts Spine with Abscess
Vertebral body destruction with loss of IVD space with adjacent collection and calcification.
 
SOLID WITH FAT DENSITY
 
Lipoma
  • Painless progressive mass, well-encapsulated isointense to fat.
    14
 
Liposarcoma
  • Fast growing; Adults.
  • Soft tissue admixed with fat.
 
Lipoblastoma
  • 90% <3 yrs.
  • Areas of increase SI on T2WI
  • Fat separated by septa.
 
SOLID WITHOUT FAT
 
 
Schwannoma and Neurofibroma
  • Plexiform neurofibroma associated with neurofibroma.
 
Neuroblastoma
  • Arises from sympathetic chain
  • Children
  • Calcification present in 90%
  • Horner's syndrome.
 
Thyroid Carcinoma
  • Mass is contiguous with thyroid and has infiltrating margins and obscures soft tissue plane.
 
Pancoast Tumor
Mass lesion in lung apex with destruction of 1st rib.
  • Patient presents with Pancoast syndrome.
 
Metastatic Lymph Node Mass
Primary lesion can be localized.15
 
Others
 
Hemangioma
Compressible mass lesion, multiple small cystic spaces, phlebolith is present, vascular enhancement is present.
 
Cervical Rib
Extra rib is seen to arise from transverse process of C7.
 
1.2 MEDIASTINAL MASSES
Common
Rare
Anterior
1.
• Tortuous innominate artery
• Innominate artery aneurysm
• Lymph node
Parathyroid adenoma
• Retrosternal goiter
Lymphangioma
• Fat deposition
2.
• Lymph node enlargement
• Sternal mass
• Lipoma
• Aneurysm of ascending aorta
• Hemangioma
• Thymoma
• Teratoma
3.
• Epicardial fat pad
• Morgagni hernia
• Diaphragmatic hump
• Pleuropericardial cyst
Middle
4.
• Lymph node enlargement
• Tracheal lesion
• Aortic arch aneurysm enlarged pulmonary artery
• Cardiac tumor
• Dilatation of SVC
• Bronchogenic cyst
Posterior
5.
• Neurogenic tumor
Pharyngoesophageal pouch
16
6.
• Aneurysm of descending aorta
• Neurenteric cyst
• Esophageal dilatation
• Pancreatic pseudocyst
• Azygous dilatation
• Sequestrated lung
• Hiatus hernia
7.
• Neurogenic tumor
• Bochdalek hernia
• Paravertebral mass
• Extramedullary hemopoiesis
 
 
Mediastinum
Anterior Mediastinal Masses
Thyroid Tumor:-
  1. Nontoxic enlargement of the gland
  2. Thyrotoxicosis
  3. CA thyroid
  4. Hashimoto's disease
zoom view
Fig. 1.2.1: Typical sites of the common and rare mediastinal masses
17
Nontoxic enlargement of thyroid
Thyrotoxicosis
CA thyroid
Hashimoto's disease
A. Vocal cord involvement
+
B. SVC compression
+
C. Calcification
+/−
+/−
D. Rapid increase in size
hemo-rrhage cyst
-do-
++
E. Symptom severity
+/−
Clinical manifestation
+
F. Orbital lesion
+
 
Thymic Tumors
Normal thymic shadow
:
Triangular soft tissue mass which projects to one side of the media-stinum.
Prominent
:
• On expiratory film.
• Slightly rotated film.
Disappears
:
• Severe neonatal infection.
• After major surgery.
• Use of steroids.
 
Commonest Tumors
  1. Thymoma
    1. Benign
    2. Malignant 30%
  2. Hyperplasia of the gland
  3. Thymic cyst
  4. Thymolipoma
  5. Lymphoma
  6. Germ cell tumor
  7. Carcinoids
    18
zoom view
Flow Chart 1.2.1:
19
 
Teratodermoid Tumors
  • Dermoid cyst
  • Teratoma
    • Benign
    • Malignant
  • All arise from primitive germ cell nests in the urogenital ridge.
  • Dermoid cyst contains mainly ectodermal tissues.
  • Solid teratoma contains tissues of ectodermal, mesodermal and endodermal origin.
Dermoid cyst appears as a round or oval soft tissue mass, which may show peripheral rim or central nodular calcification. A fat fluid level or a rudimentary tooth is diagnostic radiological sign. Teratoma appears as a lobulated soft tissue mass which on CT shows a mass of mixed attenuation containing soft tissue, cyst fluid, fat, calcification or bone.
 
PLEUROPERICARDIAL CYST
  • Anterior mediastinal mass.
  • 75% occur in right anterior cardiophrenic angle.
  • Cysts have thin walls, which contain clear fluid.
  • These changes shape with respiration.
 
D/D OF SOFT TISSUE LESIONS IN RIGHT ANTERIOR CARDIOPHRENIC ANGLE
(See Flow Chart next page).
 
Morgagni Hernia
  • Persistent developmental defect in the diaphragm anteriorly.
  • Anterior mediastinal mass.
  • May contain omentum or transverse colon.
    20
    zoom view
    Flow Chart 1.2.2:
    21
  • Appears as a soft tissue mass
  • Containing either gas or air-fluid level or fat.
  • Diagnosis is confirmed by barium meal and follow through or barium enema.
 
MIDDLE MEDIASTINAL MASSES
 
Lymph Node Enlargement
 
Metastatic
  • Intrathoracic
    • Bronchial CA
    • Esophageal CA
  • Extrathoracic
    • Breast, renal
      Adrenal, Testicular
      Tumor of pharynx and larynx.
  • Lymphoma
  • Leukemia
  • Sarcoidosis: Bilateral hilar masses with well-defined outline. These show egg shell calcification.
  • Primary tuberculous infection produces an area of consolidation in one of the lobes with unilateral hilar mass and an associated pleural effusion.
  • Low attenuation areas due to cyst formation or necrosis are seen in lymph nodes involved with Hodgkin's disease and metastatic testicular or squamous cell tumors. Particularly after treatment with radiotherapy or chemotherapy.
 
Aortic Aneurysm
These produce either widening of the mediastinum or a round or oval soft tissue mass in any part of the mediastinum with 22well-defined outline. Curvilinear or peripheral calcification may be due to syphilitic aortitis or atherosclerosis. May cause pressure erosion defect of the sternum or anterior scalloping of one or two vertebral bodies. The subintimal flap and false lumen of a dissecting aneurysm can be demonstrated by CT.
 
Tortuous Innominate Artery
It occurs in 20% of the elderly patients with hypertension and produces widening of the superior part of the mediastinum on the right without displacement of the trachea to the left.
 
Bronchogenic Cyst
  • Middle or posterior mediastinal mass.
  • Majority occur around the carina in the paratracheal, tracheobronchial or subcarinal region.
  • Can alter in shape on respiration.
  • Pericardial defect may occur in association.
 
Tracheal Tumors
Tracheal tumors include carcinoma, plasmacytoma. They narrow the tracheal lumen and appear as soft tissue mass.
 
POSTERIOR MEDIASTINAL MASSES
 
Neurogenic Tumors
 
Adults
Neurofibroma
Neurilemmoma.
 
Children
Neuroblastoma
These may be asymptomatic or may produce back pain and may even extend through an intervertebral foramen into the 23spinal canal (dumb-bell tumors) to produce spinal cord compressions.
Shape
Calcification
Dumb-bell
Neurofibroma
Rounded
+/−
+
Neurilemmoma
-do-
Neuroblastoma
elongated
Central spicules or peripheral rim
+
Involvement of the posterior ribs or adjacent thoracic vertebrae – produce ribs splaying, localized pressure erosion defect of one or two vertebral bodies and ribs notching.
 
HIATUS HERNIA
  • Commonest cause of a mediastinal mass on a chest radiograph in an elderly patient. Soft tissue mass with an air-fluid level.
  • Lies to the left of the midline.
  • Contents could be liver, omentum and small intestine.
 
ESOPHAGEAL LESIONS
Present with dysphagia.
Pharyngoesophageal pouch: Soft tissue mass with an air-fluid level, lies in the midline, displaces trachea forwards.
Carcinoma/leiomyoma: Soft tissue mass with an air-fluid level, behind the heart.
Achalasia: Large soft tissue mass with air-fluid level with barium flowing in spurts. Pulmonary consolidation/Bron-chiectasis may be present.
 
PARAVERTEBRAL LESIONS
Involves the thoracic vertebrae or intervertebral disk space. 24They appear as an elongated or lobulated soft tissue mass with a well-defined outline.
D/D would be:
  • Hematoma
  • Pyogenic abscess
  • Tubercular abscess
  • Multiple myeloma
  • Lymphoma
  • Metastasis
  • Extramedullary hematopoiesis.
 
Bochdalek Hernia
Persistent develop mental defect in the diaphragm posteriorly.
Occurs in the left hemidiaphragm.
Small hernias usually contain retroperitoneal fat, kidney or spleen, which appears as a soft tissue mass in the posterior costophrenic angle.
Larger hernias may contain jejunum, ileum and colon.
 
Neurenteric Cysts
Result due to partial or complete persistence of the neur-enteric canal or its incomplete resorption include, gastrointestinal duplication, enteric cyst, neurenteric cyst, anterior meningocele and cysts of the canal.
 
Pancreatic Pseudocyst
  • Posterior mediastinal mass.
  • Round/oval soft tissue mass behind the heart.
  • A left basal pleural effusion or atelectasis in the lower lobes may result.
    25
  • Extramedullary hemopoiesis.
    Appears as lobulated paravertebral soft tissue mass behind the heart.
 
1.3 SUPERIOR MEDIASTINAL MASSES—DIFFERENTIAL DIAGNOSIS
zoom view
Fig. 1.3.1:
Contents→
  1. Trachea and esophagus
  2. Muscles – sternohyoid, sternothyroid and lower ends of longus colli.
    26
  3. Anterior arch of aorta, brachiocephalic artery. ICC and left subclavian artery.
  4. Veins—Right and left brachiocephalic vein, upper half of SVC.
  5. Nerves—Vagus, phrenic, cardiac nerve, right laryngeal nerve.
  6. Thymus
  7. Thoracic duct
  8. LNs-paratracheal, brachiocephalic, TB
 
 
 
Criteria for Superior Mediastinum Widening→
>8cm in the transverse diameter
>25% of the thoracic diameter at that level.
  1. Retrosternal goiter: Less than 5% of enlarged thyroid in neck. Extend into mediastinum due to nontoxic enlargement, thyrotoxicosis, Carcinoma Hashimoto's disease.
    • Soft tissue swelling that moves on swallowing
    • Dysphagia, stridor if benign, vocal cord paralysis or SVC compression-malignancy
    • Patients present soft tissue mass in anterior part; extend down from the neck
    • Outline well-defined in mediastinum but fades off into neck
    • Displacement and compression of trachea to left, 20% are retrotracheal
    • Ca++ nodules, linear or crescent pattern
    • CT mass of mixed attenuation extending from one of lower pole of thyroid
    • Radionucleide scan 99 Tc per technetate on 123 I NaI
    • MRI – Diagnostic
  2. Thymus – Normal thymus—most common in infants
    Most common in adult benign and malignant thymoma.
    Associated with myasthenia gravis, red cells aplasia or decreased granulocytes.27
    Plain X-ray chest −Ve
    CT – Grossly asymmetrical lobular configuration.
    – Homogenous with mild contrast enhancement
    – Less commonly decreased attenuation areas-Hemorr-hage/Necrosis/cyst Ca++-occasionally
    MRI = T1 = Med. SI, T2 = > fat
    Thymic Hyperplasia
    Seen in 2/3rd of myasthenia gravis
    CT = symmetric diffuse enlargement
    MR = same signal as normal gland
    Enlargement of thymus may also be seen in thymic cyst, thymolipoma, lymphoma, germ cell tumor and carcinoid.
  3. Teratodermoid tumors/germ cell tumor – Extragonadal germ cell tumor located within or adjacent to thymus.
    Most common germ cell tumor in sup. mediastinum is dermoid cyst and benign and malignant teratoma. CxR round or oval soft mass with well-defined border and may contain peripheral rim or central nodules of Ca++. III CT fat fluid level, Ca++ well-defined border and soft tissue attenuation highly S/O germ cell tumor.
    Malignancy – more solid component and aggressive features.
  4. Lymph node enlargement
    Widened mediastinum may have lobulated margins in case of LN enlargement.
    Hodgkin/NonHodgkin disease – paratracheal and Tracheo-bronchial, asymmetrical widening of middle part of superior mediastinum
    • Associated feature—parenchymal lung disease
    • Ca++ in LN seen after irradiation
    TB-U/L paratracheal lymph adenopathy without obvious mediastinum or pleural involvement seen in immunocompromised patients.
    In adult/children area of consolidation/caseation28
    Fungal disease histoplasmosis, coccidioidomycosis, blastomycosis
    • Enlargement of Hila or paratracheal LN
    • Ca++ in healing histoplasmosis
    Sarcoidosis—B/L lobulated hilar mass
    Metastasis
    Primary tumor is usually intrathoracic – Esophagus/Bronchus
    Benign—
    in adult
    papilloma
    chordoma - Ca++ Smooth, well-defined and
    Fibroma < 2 cm in diameter
    Hemangioma
    Mucus plug - decreased alternation, mixed with air and will change in position and resolve after coughing.
    Malignant - sq cell Ca and adenoid cystic Ca2. – Most common a smooth or irregular intraluminal mass with asymm. Narrowing of tracheal lumen is seen.
  5. Aneurysm and dissection of arch of aorta—true, pseudo, post-traumatic atherosclerotic, post-traumatic elderly, fusiform.
    Younger, contained by adventitia only, saccular
    c.presentation→Asymptomatic
    Symptoms—enlarged compresses adjacent structure
    C×R = Widening with or without Ca++
    CT = Saccular and fusiform dilatation of segment of aorta.
    –>4cm; use short axis diameter
    • Ca++ in aortic wall, peripheral
    • Intraluminal thrombus-crescentic/circumferential
    • Displacement of adjacent structure = Trachea, bronchus and pul artery, Sup. Vena cava, esophagus, bony erosion, growth rate 5.6 cm/year
      29
      Aortic dissection emergency situation:
      Peak 7th–8th Decade
      Most common predisposing condition is hypertension– congenital heart disease, coarctation, bicuspid AV
      Intimal tear → blood enter into the aortic wall and creates a false and true lumen.
      CXR wide mediastinum aortic contour displaced, intimal Ca++.
      CT = Internal displacement or intimal Ca++
      Visible internal flap increased in attenuation
      High density thrombus in false lumen if actue hemo-rrhage.
      CECT—Contrast filled true and false lumen separated by intimal flap
      Delayed enhancement of false lumen because of slow flow.
      MR—very well-demonstrate the intimal flap
      Aortography—Highly accurate.
  6. Dilatation of SVC and other veins
    Dilatation of SVC seen in raised CVP
    CCF
    Tricuspid valve disease
    Mediastinal mass
    Constrictive pericarditis
    TAPVD—Supracardiac variety. All the pulmonary veins open into large ascending vein on left side which is a remnant of embryonic. Left SVC. This connects into the left brachiocephalic vein which then passes into the right sided SVC and into the RA.
  7. A pharyngoesophageal pouch/Zenker's diverticulum
    CXR = Soft tissue mass in posterior part of superior mediastinum which contain an air-fluid level
    Soft tissue mass lies in the midline and displaces the trachea forward.
    Ba-esophagogram—Confirm the diagnoses.30
    zoom view
    Flow Chart 1.3.1: Cardiophrenic Angle Masses
    31
  8. Fat deposition—superior mediastinum widening and epicardial fat pad seen in obese adult patient, Cushing disease, steroid therapy.
    CT = shows an excessive amount of mediastinal fat
  9. Tracheal Mass—positive with nonspecific symptoms like cough, dyspnea, stridor, wheezing.
    CXR = Not very helpful.
    Benign – in adult
    Hemangioma
    Mucus plug-decrease attenuation, mixed with air and will change in position and resolve after coughing.
    Malignant-Sq cell Ca and adenoid cystic Ca = Most common
    A smooth or irregular intraluminal mass with asym-metric narrowing of tracheae lumen is seen
  10. Neurogenic tumor.
    Adult—NF and schwannoma—peripheral intercostal nerve children—ganglioneuroma and neuroblastoma - which arise is thoracic sympathetic ganglia.
    CXR—A round or oval soft tissue mass in paravertebral gutter which usually project to one side of mediastinum.
    Neuroblastoma—central spicules or peripheral rim Ca++ splaying of post ribs.
    Pressure erosion, defect of vertebral-bodies
    Rib notching
    Enlargement of an intervertebral foramen
    CT = solid mass of soft tissue attemation, may contain Ca++ and involve the adjacent bone.
    MRI = intraspinal extension.
    MRI = Transaxial SE
    GRF/phase velocity mapping
    32
 
1.4 DIFFERENTIAL DIAGNOSIS OF ANTERIOR MEDIASTINAL MASS
Anterior mediastinum lies anterior to anterior pericardium and trachea. For ease of differential diagnosis it can be divided into 3 areas.
zoom view
Fig. 1.4.1:
Region 1
Region 2
Region 3
1. Tortuous innomi-nate artery
• L N enlargement
• Epicardial fat pad
2. Lymph nodes
• Aneurysm of aorta
• Diaphragmatic hump
3. Retrosternal goiter
• Thymoma
• Teratodermoid tumors
• Pleuropericardial cyst
33
4. Fat deposition
• Morgagni's hernia
5. Aneurysm of innominate artery
• Sternal mass
Lipoma
6. Parathyroid adenoma
• Hemangioma
7. Cystic hygroma or lymphangioma
 
 
Salient Features
 
Region 1
  1. Thyroid tumor (Retrosternal Goiter)
    • Less than 5% goiters extened into the mediastinum.
    • Mostly females presenting with soft tissue swelling, dysphagia, stridor.
    • Chest X-ray shows oval soft tissue mass in superior part of anterior mediastinum fading off into neck.
    • Well-defined smooth or lobulated.
    • Central nodular, linear calcification.
    • Displacement and compression of trachea.
    • CT shows mass of mixed attenuation with cysts and calcifications, contiguous with one of the poles of thyroid.
  2. Lymph node enlargement.
    May be due to lymphoma, metastasis or infection.
    • Widening of mediastinum on chest X-ray.
    • Lobulated soft tissue mass due to indentation by ribs.
    • Calcification may be present.
    • Lymphadenopathy else where in body.
    • CT shows discrete round or slightly irregular densities of various sizes +/− enhancement and necrosis.
      34
  3. Fat deposition
    • Cushing's disease, corticosteroid therapy.
    • Widening of superior mediastinum on chest X-ray.
    • CT shows excessive amount of mediastinal fat with density − 50–100 HU.
  4. Tortuous innominate artery or aneurysm
    • Common in elderly.
    • Widening of superior mediastinum.
    • CT shows dilatation of innominate artery
  5. Lymphangioma/cystic hygroma
    • Mainly in children.
    • Transilluminating soft tissue swelling in root of neck.
    • Chest X-ray shows: Oval soft tissue mass extending into neck.
    • Alters shape on respiration but does not displace trachea.
    • U/S and CT shows cystic septated mass.
  6. Parathyroid adenoma
    • Hypercalcemia with hyperparathyroidism.
    • Usually small with normal chest X-ray.
    • Confirmed by radionuclide scan with 201 Tl chloride with increased activity.
 
Region 2
  1. Thymoma: usually adults.
    • Can present with myasthenia gravis (10–15%)
    • Round oval and smooth or lobulated.
    • May have nodular or rim calcification.
    • CT shows mixed attenuation mass with calcification and cysts.
  2. Teratodermoid Tumor: Commonly dermoid cysts and benign and malignant teratomas.
    35
    • Anterior mediastinal mass in young adult patient dyspnea, cough, chest pain.
    • Round or oval soft tissue mass, projects to one side.
    • Calcification especially rim, fragments of bone and teeth are diagnostic.
    • Fat with fat-fluid level.
  3. Lymph node enlargement
  4. Aneurysm of ascending aorta
    • Widening of mediastinum or mediastinal mass
    • Well-defined outline
    • Peripheral rim of calcification.
    • Pulsatile mass on fluoroscopy.
    • Pressure erosion of sternum.
    • CT shows dilated aorta with blood of higher atten-uation.
  5. Sternal mass
    Metastasis, plasmocytoma, chondrosarcoma, osteo-myelitis.
    • Soft tissue mass with sternal destruction.
    • Tumor new bone formation or lytic expansion of sternum.
    • Collection in anterior mediastinum with sternal destruction in osteomyelitis.
  6. Lipomas
    • Round or oval soft tissue density mass with low density.
    • Alters shape on respiration.
    • CT shows solid mass of fatty attenuation.
  7. Hemangioma
    Widening of mediastinum, round or oval soft tissue mass, phleboliths are diagnostic.
 
Region 3
  1. Epicardial fat pad
    36
    • Especially in obesity.
    • Triangular opacity in cardiophrenic angle.
    • Less dense due to fat.
    • CT shows fat density and is diagnostic.
  2. Diaphragmatic hump
    • Localized eventration
    • Common on anteromedial portion of right dome.
    • Portion of liver extends into it.
    • Can be confirmed by U/S.
  3. Pleuropericardial cyst
    • Spring water cyst or pericardial diverticulum.
    • 75% in Rt. anterior cardiophrenic angle.
    • Round/oval/triangular soft tissue mass.
    • Alters shape on respiration.
    • U/S or CT shows transsonic or cystic mass adjacent to pericardium with density 0–20 HU.
  4. Morgagni's hernia
    • 90% in Rt anterior cardiophrenic angle.
    • Round or oval soft tissue mass.
    • Lower radiographic density than expected for its size.
    • Larger hernias contain transverse colon which appear as soft tissue mass with air-fluid level.
    • Diagnosis by u/s, confirmed by barium meal exami-nation or CT.
 
ANTERIOR MEDIASTINAL MASS
 
Children
 
Congenital
  • Normal thymus
    • Sail sign +ve
    • Wave sign +ve
    • Notch sign +ve
      37
  • Cystic hygroma
    • Cystic septated mass in neck and mediastinum
  • Morgagni's hernia.
    • Soft tissue density in cardiophrenic angle.
  • Neoplastic
  • Soft tissue density mass.
    • With discrete L.N. +/− enhancement
      +/− calcification.
    • L.N elsewhere
 
Lymphoma
  • With calcifications fat, tooth, cyst.
  • Teratodermoid tumor.
  • Inflammatory
    • Lymph nodes with rim enhancement.
    • Collection or abscess.
 
ANTERIOR MEDIASTINAL MASS
 
Adults
Widening of mediastinum on X-ray with lobulated soft tissue density mass on CT.
 
Lymphoma
Multiple discrete or matted L.N +/− enhancement, calcification, LN elsewhere.
 
Thymoma
Soft tissue calcification cysts
Associated with myasthenia gravis
Teratodermoid
Cyst calcification
Tooth, fat, young adult.38
 
Thyroid
Mixed attenuation contiguous with thyroid pole.
Widening with fat density on CT
Epicardial fat pad
Lipoma
Widening with cystic density
Pleuropericardial cyst.
  • Abscess
 
Vascular
  • Aortic aneurysm
  • Hemangioma
  • Mass
 
1.5 MIDDLE MEDIASTINAL MASSES
 
 
Children
  1. Lymph nodes
    • Neoplastic
    • Inflammatory
  2. Foregut duplication cysts
    • Bronchogenic cyst
    • Esophageal duplication cyst
    • Neurenteric cyst
  3. Cystic hygroma
  4. Vascular
    • Vena cava enlargement
 
Adult
  1. Lymph nodes
    • Neoplastic
      39
    • Inflammatory
    • Inhalation disease
  2. Primary tumors
    • Carcinoma of trachea
    • Bronchogenic carcinoma
    • Esophageal tumor
      • Leiomyoma, carcinoma
    • Mesothelioma
  3. Vascular lesions
    • Aortic aneurysm
    • Distended arteries or veins
  4. Bronchogenic cyst.
 
LYMPH NODES
  • 90% of masses in the middle mediastinum are malignant.
  • Paratracheal, tracheobronchial, subcarinal and broncho-pulmonary groups. Middle mediastinal lymph node groups.
  • Often asymptomatic, may produce cough, dyspnea and wt. loss.
  • It appears as widening of right paratracheal stripe, bulge in aortopulmonary window, lateral displacement of azygoesophageal line, lobulated widening of mediastinum and unilateral or bilateral lobulated hilar soft tissue mass.
 
Neoplastic
  • Hodgkin's disease, non-Hodgkin's disease and the lymphatic leukemias produce middle mediastinal lymphadenopathy which is often unilateral.
 
Hodgkin's Disease
On CT, nodal involvement ranges from enlarged discrete lymph nodes to large conglomerate masses.40
  • Thymic involvement is seen in 70% of cases.
  • Involvement of superior mediastinal lymph node was seen in 98% of patients with intrathoracic disease.
 
Non-Hodgkin's Disease
  • Noncontiguous spread, more advanced disease, other sites involvement more common.
  • Involvement of superior mediastinum in <75% cases.
    Parenchymal involvement of lungs also occurs and calcification occasionally develops in Hodgkin's disease after radiation.
  • Fungal infections like histoplasmosis, coccidioidomycosis, blastomycosis produce hilar or paratracheal mediastinal adenopathy with or without pulmonary involvement.
  • Other infective and inflammatory causes include infectious mononucleosis, measles, whooping cough, mycoplasma, adenovirus and lung abscess.
 
Inhalation Disease
  • Silicosis-egg-shell calcification
  • Coal worker's pneumoconiosis
  • Berylliosis
 
Foregut Duplication Cyst
Bronchogenic cyst—is a thin-walled foregut cyst lined by ciliated columnar epithelial cells of respiratory origin. Which contains viscid mucoid material.
  • Usually seen as an incidental mass in a young adult.
  • Rarely the cyst can become affected in children and rupture into the bronchial tree and hemorrhage into the cyst can also occur.
  • Majority occur around carina in subcarinal region but can occur in right paratracheal or posterior mediastinum.
  • Appear as well-defined round or oval soft tissue mass which can alter in shape on respiration.
    41
Diagnosis is confirmed by CT or MRI. CT shows a thin- walled cyst containing fluid of either low attenuation (0–20 HU) or mucinous material containing cysts (20–50HU).
 
Esophageal Duplication Cyst
  • Less common than bronchogenic cysts, usually larger and usually situated to the right of the midline extending into the posterior mediastinum.
  • May be incidental finding or produce symptoms related to esophageal or respiratory compression. May contain ectopic gastric mucosa causing ulceration, hemorrhage or perforation.
 
Neurenteric Cyst
  • Located in middle or posterior mediastinum
  • Contain neural tissue and maintain a connection with spinal canal.
  • Commonly right sided and associated with vertebral-body anomalies like hemivertebrae, butterfly vertebrae, and scoliosis which are usually superior to it.
    CT, MRI-for defining extent, relationship to other structure and defining intrinsic contents which may be watery or viscous.
 
Cystic Hygroma
  • 5% cases extend into the mediastinum from the neck.
  • Most present at birth.
  • Cystic with septation and some solid components on all imaging modalities.
 
Thoracic Aortic Aneurysm
  • Usually seen as an incidental mediastinal abnormality on a chest radiograph in elderly patients.
    42
  • It appears as either widening of the mediastinum or as a well-defined round or oval soft tissue mass in any part of the mediastinum often with curvilinear calcification in its wall.
  • Displacement of rim of calcification—Aortic dissection.
  • Pressure erosion of sternum or vertebral bodies.
  • Diagnosis confirmed by CT or MRI which shows—aorta >4cm and containing contrast-enhanced blood in its lumen with surrounding mural thrombus of lower attenuation and calcification in its wall.
 
Other Arterial Abnormalities
  • Dilatation of the main pulmonary artery due to pulmonary artery hypertension, pulmonary valve stenosis with post- stenotic dilatation or a pulmonary artery aneurysm also produces an apparent left hilar mass.
  • A tortuous innominate artery produces widening of the superior mediastinum on the right and an aneurysm of the innominate or subclavian arteries produce widening of the mediastinum on the left often simulating a left hilar mass.
 
Venous Abnormality
  • Dilated superior vena cava produces slight widening of the mediastinum on the right usually caused by congestive, cardiac failure, tricuspid valve disease, etc.
  • A persistent left sided superior vena cava produces slight widening of the mediastinum on left side.
  • A dilated azygous vein—oval soft tissue mass in the right tracheobronchial angle.
    43
 
Metastasis
  • Most mediastinal lymph node metastasis arise from a primary thoracic neoplasm, most commonly bron-chogenic carcinoma.
  • Generally the lymph node are on the same side.
  • In patient with central sq. cell Carcinoma or small cell carcinoma the hilar/mediastinal mass may be the only abnormality on plain X-ray or CT.
  • In patients with extrathoracic neoplasms, intrapulmonary metastasis are 10 times more common than nodal metastasis.
  • Most common tumors associated with nodal metastasis are—
    • Genitourinary (renal and testicular)
    • Head and neck
    • Breast
    • Melanoma
  • Isolated lymph node involvement seen in 60% cases.
  • Hilar and right paratracheal are most common involved.
 
Inflammatory
Tuberculosis: Primary tuberculosis produces an area of consolidation in one lobe with unilateral enlargement of the bronchopulmonary, paratracheal, and subcarinal lymph node.
  • Pleural effusion also occurs and complete calcification of the lymph node may develop as healing occurs.
 
Sarcoidosis
  • Enlargement of the bronchopulmonary and paratracheal lymph node, which usually are bilateral.
  • Enlarged lymph node in locations like subcarinal, anterior and posterior mediastinum may be seen particularly if CT is performed.
    44
zoom view
Flow Chart 1.5.1:
45
 
1.6 D/D POSTERIOR MEDIASTINAL MASSES
 
 
Mediastinum
  • Anterior—in front of the anterior pericardium and trachea
  • Middle—within the pericardium including the trachea
  • Posterior—lies behind the posterior pericardium and trachea
zoom view
Fig. 1.6.1:
 
DD's
Region 5
• Neurogenic tumors
• Pharyngoesophageal pouch
6
• Hiatus hernia
• Neurenteric cyst
• Aneurysm of descending aorta
• Esophageal dilatation
• Sequestrated lung segment
46
• Dilatation of azygous vein
7.
• Neurogenic tumors
• Bochdalek's hernia
• Paravertebral mass
• Extramedullary hemopoiesis
 
Neurenteric Cyst
  • Partial or complete persistence of the neurenteric canal or its incomplete resorption.
    • Gastrointestinal reduplication
    • Enteric cysts
    • Neurenteric cysts
    • Anterior meningocele
    • Cysts of the cord
  • Associated spinal anomalies
    • Block vertebra
    • Hemivertebra
    • Butterfly vertebrae
    • Spina bifida
  • Usually present in infants.
  • Respiratory distress
  • Feeding difficulties
  • Cysts—appears as oval or rounded soft tissue mass in posterior mediastinum.
  • Anterior meningocele: diagnosed by CT–myelo, prone scan
  • Esophageal duplication cyst – Barium swallow – ectopic gastric mucosa – Tc 99m positive
 
Pertechnetate Scan
  • Neurenteric cyst can be diagnosis by USG/CT/MRI/— usually right sided
    47
 
Dilated Azygous Vein
  • Oval soft tissue mass in right tracheobronchial angle.
  • Caused by – increased central venous pressure.
    • Superior or inferior vena cava obstruction
    • Portal hypertension
    • Congenital azygous continution of IVC
    • D/D- Enlarged azygous lymph node
    • Azygous vein – decrease in size – in erect position
    • On deep inspiration
    • During maneuver
 
Esophageal Lesions
  • Pharyngoesophageal pouch or Zenker's diverticulum:
    • Round mass containing air-fluid level in the superior part of posterior mediastinum usually in the midline displaying the trachea anteriorly.
  • Leiomyoma/Leiomyosarcoma – soft tissue mass
  • Lower esophageal diverticulum – rounded mass with air- fluid level behind the heart
  • Dilated esophagus – Widening of the posterior media-stinum on right side from thoracic inlet to diaphragm with lateral displacement of azygoesophageal line. Dilated esophagus displaces the trachea anteriorly.
  • Air-fluid level with nonhomogenous mottled appearance of food mixed with air diagnosis confirmed by barium swallow or CT.
 
Paravertebral Lesions
  • Traumatic wedge compression fracture of vertebral body with paraspinal hematoma – H/o trauma.
  • Pyogenic/tubercular paravertebral abscess – narrowing of disk space with involvement of vertebral endplates.
  • Smooth fusiform bilateral or unilateral soft tissue mass
  • Metastasis – bone destruction with pathological fracture
    48
  • Extramedullary hematopoiesis – Lobulated mass in chronic hemolytic anemia
  • Lymphoma
 
Bochdalek's Hernia
  • Developmental defect in posterolateral part of left hemi-diaphragm
  • Contents of the hernial sac includes retroperitoneal fat, kidney, spleen, splenic flexure.
Large or small intestine, stomach, colon may also herniate
  • Mediastinal shift/ipsilateral hypoplastic lung
  • Thirteen pair of ribs may be associated.
 
Neurogenic Tumors
  • Peripheral nerves
  1. Nerve sheath tumor
    • Neurofibroma
    • Schwannoma or neurilemmoma
    • Neurofibrosarcoma
    • Malignant schwannoma
  2. Ganglion cell tumors
    • Ganglioneuroma benign (> 10 yr)
    • Ganglioneuroblastoma (5–10 yr)
    • Neuroblastoma (<5 yr) (Most malignant)
  3. Paraganglionic nerve tissue tumors
    ↓ -(rarest)
    • Chemodectomas
    • Pheochromocytomas
      • 30% malignant
      • Childhood or young adult patient
      • Asymptomatic, back pain, spinal cord compression.
        49
      • Can be multiple in the setting of neurofibromatosis— association with lateral thoracic meningocele.
Radiological features – Well-defined oval soft tissue mass in paravertebral gutter
Nerve sheath tumors – Circular, calcification – rare.
Ganglion cell tumors – Elongated, central spicules or nodules of calcification, enlargement of intervertebral fora-men, scoliosis.
 
Hiatus Hernia
  • Usually an incidental findings in an elderly patient
  • Often asymptomatic
    Clinical features – Dyspnea, retrosternal chest pain, epigastric discomfort, iron deficiency anemia.
    CXR – Round soft tissue mass with air or air-fluid level, behind heart usually to the left of midline
    zoom view
    Flow Chart 1.6.1:
    50
    zoom view
    Flow Chart 1.6.2:
    51
    zoom view
    Flow Chart 1.6.3:
    • Larger hernias may contain small intestine, colon, liver
    • Diagnosis – confirmed by lateral chest X-ray, barium or CT.
 
1.7 CHEST WALL ABNORMALITIES
Congenital and developmental anomalies
Tumors
Soft tissue tumors
• Pectus excavatum
• Pectus cavinatum
• Poland syndrome
• Cervical rib
• Cleidocranial dysplasia
• Lipomas
• Neurogenic tumors
• Hemangiomas
• Desmoid tumors
  • Lymphomas
• Sarcomas
Inflammatory and infectious
• Pyogenic
• TB
  • Osseous tumors
• Osteochondroma
• Enchondroma
52
• Actinomycosis
• Aspergillosis
• Osteoblastoma
• Chondrosarcoma
• Myeloma
• Plasmacytoma
Nonneoplastic osseous
• Fibrous dysplasia
• Paget's disease
• Giant cell tumor
• Aneurysmal bone cyst
 
PECTUS EXCAVATUM
  • Most common congenital anomaly of sternum.
  • Decrease prevertebral space—left hand deviation of heart with axial rotation
    • Increased parasternal soft tissue in right inferomedial hemithorax.
    • Lateral chest X-ray and CT quantify the severity.
 
PECTUS CAVINATUM
  • Protrusion of sternum anterioly
  • May be seen in isolation or with cyanotic congenital heart disease.
 
CERVICAL RIB
  • Supernumerary rib that articulates with cervical type of transverse process.
 
CLEIDOCRANIAL DYSOSTOSIS
  • Incomplete ossification of ribs with defective development of pubic bones, vertebral column and long bones.
    53
 
POLAND SYNDROME
  • Partial/total absence of greater pectoral muscle and ipsilateral syndactyly.
  • Atrophy of ipsilateral fifth ribs, absence of smaller pectoral muscle, aplasia of ipsilateral breast/nipple, simian crease of affected extremity.
 
Inflammatory and Infectious Disease
  • Primary infection rare and seen in diabetes mellitus, immunosuppression, trauma and i.v drug abuses.
  • Secondary infection due to disease processes in lung or to pleurae, empyema more common.
  • May produce parenchymal infection, pleural effusion, chest wall masses, rib destruction and even cutaneous fistula, air-fluid levels may be seen in soft tissues. Patient usually have febrile cause.
 
TUMORS OF CHEST WALL
  • Primarily soft tissue tumors are rare.
  • In adults, most common benign soft tissue neoplasm is lipoma and most common malignant neoplasms are fibrous sarcoma and MFH.
    In children, PNET(Askan) tumor, rhabdomyosarcoma and extraosseous Ewing's are most common malignant soft tissue tumors.
  • Secondary tumors are more common in thoracic skeleton.
  • Majority of osseous lesions are in ribs, large numbers are metastatic.
  • Osteochondroma is most common benign tumor of carti-lage bone. Most common malignant tumor is chondro-sarcoma.
    54
  • Majority of lesions arising from sternum are malignant and represent chondrosarcoma most often.
  • Lesions of thoracic vertebrae are invariably metastatic.
  • Most common tumors to produce pattern of chest wall mass with bone destruction are metastases and small round cell tumors (multiple myeloma), Ewing's tumor and neuroblastoma. The differential diagnosis in adults is mets v/s myeloma, while in a child pattern in more s/o Ewing's tumor or metastatic neuroblastoma.
 
Radiologic Differentiation of Chest Wall Tumors
 
Benign
Imaging findings
Tumor type
• Fat attenuation/intensity
• Calcification
  • Skeletal
    • Amorphous
    • Cartilaginous apical cap
  • Extraskeleton, punctate
• Lipoma
• Fibrous dysplasia
• Osteochondroma
• Cavernous heman-gioma
• Cortical thinning-fluid- fluid levels
• Cortical expansion, sclerotic band
• Rib erosion, well-defined contours, extraskeletal location
• Location at costochondral junction
• Location in paravertebral region
• Location in shoulder region
• ABC or GCT
• Ossifying fibromyxoid tumor or chondromy-xoid fibroma
• Schwannoma or nonossifying fibroma
• Osteochondroma
• Ganglioneuroma or paraganglioma
• Spindle cell lipoma
55
 
Malignant
Imaging
Tumor
• Fat component
• Calcification
  • Skeletal
  • Rings and arcs
  • Flocculent or stippled
  • Centrally dense
• Liposarcoma
• Chondrosarcoma
• Osteosarcoma
• Extraskeletal
  • Heterogeneous
  • Speckled
• Ganglioneuroma or neuroblastoma
• Proximal type epitheliod sarcoma
• Diffuse osteolytic changes
• Ill-defined mass
  • Eccentric growth, in children and young adults
  • Fluid-fluid levels and calcification in adolescents and adults
  • Chronic lymphedema
  • Infiltrative growth
• Nonspecific findings
• Myeloma
• Ewing sarcoma
• Synovial sarcoma
• Angiosarcoma
• Malignant lymphoma
• LMS. RMS, MFH.etc.
 
1.8 SUPERIOR RIB NOTCHING
 
CLASSIFICATION (Sargent et al)
  1. Normal
  2. Disturbance of osteoblastic activity with decreased or deficient bone formation.
    56
    • Paralytic poliomyelitis
    • Collagen diseases
      • Scleroderma
      • Rheumatoid arthritis
      • Systemic lupus erythematosus (SLE)
    • Exostosis
    • Neurofibroma
    • Surgery
    • Osteogenesis imperfecta
    • Coarctation of aorta
    • Marfan's syndrome
    • Radiation damage
    • Quadriplegia
  3. Disturbance of osteoclastic activity with increased bone resorption.
    • Hyperparathyroidism
    • Hypovitaminosis - D
  4. Idiopathic
 
SALIENT FEATURES
 
 
Poliomyelitis
  • Limb deformities and muscle atrophy seen particularly involving the pectoral muscles and shoulder girdle.
  • Rib notching seen in chronic cases usually involving 3rd–9th ribs.
  • Unilateral hypertransradiant hemithorax
  • Scoliosis
 
Rheumatoid Arthritis
  • More common in females.
  • Symmetrical arthritis especially involving the MCP and PIP joints of hands and feet and wrist.
    57
  • Absence of lateral end of clavicle or pencil pointing may be seen.
  • Caplan syndrome—Multiple nodules in lung
  • Subcutaneous nodules.
 
Systemic Sclerosis
  • Raynaud phenomenon
  • Subcutaneous calcification-especially in the fingertips
  • Esophageal abnormalities—dilatation, atonicity, poor or absent peristalsis
  • Symmetric erosions on superior surface, predominate along the posterior aspect of 3–6 ribs.
  • Terminal phalanx resorption
  • Skin thickening.
 
SLE (Systemic Lupus Erythematosus)
  • Mostly females, butterfly rash
  • Polyarthritis: Bilateral and symmetrical involving the small joints of the hand, knee, wrist.
  • MCP and PIP joint involvement—No erosions.
  • Recurrent pleural effusion often with pleurisy resulting in elevation of a hemidiaphragm and plate atelectasis at base.
 
Osteochondroma
  • 10–20 yrs of age
  • Well-defined protrusion with the parent cortex and trabeculae continuous with that of parent bone. Cartilage cap.
  • Most common distal femur, proximal tibia
  • Lesions arising from ribs and scapulae cause rib notching
  • Diaphyseal achalasia—Multiple lesions.
    58
 
Neurofibromatosis
  • One or more primary relatives with neurofibromas
  • Café au lait spots
  • Optic gliomas
  • Typical bone lesions—sphenoid dysplasia
    (absent greater wing or lesser wing, absent posterolateral wall of orbit)
    Tibial pseudoarthrosis.
  • Rib notching, twisted ribbon ribs, splaying of ribs.
  • Cerebral and cerebellar calcification, heavy calcification of choroid plexus.
 
Marfan's Syndrome
  • Tall stature, long slim limbs
  • Arachnodactyly
  • Joint laxity-dislocation of sternoclavicular joint and hip joint
  • Scoliosis and kyphosis
  • Pectus excavatum and cavinatum
  • Aortic sinus dilatation and aortic regurgitation
 
Osteogenesis Imperfecta
  • Osteoporotic, fragile bones often with deformities secondary to fractures and mechanical stress.
  • Often in infant or child with blue sclerae.
  • Flattened or biconcave vertebrae
  • Wormian bones
  • Rapid fracture healing with exuberant callus.
  • Wavy, thin, ribbon-like ribs with notching.
    59
 
Hyperparathyroidism
  • Subperiosteal bone erosion—particularly affecting the radial side of middle phalanx of middle finger, medial proximal tibia, lateral end of clavicle.
  • Diffuse cortical damage—Pepper-pot skull
  • Brown tumors—mandible, ribs, pelvis
  • Ribs
    • Characteristically show random notching
    • Coarse sclerosis of trabecular pattern of clavicles and ribs.
zoom view
Flow Chart 1.8.1:
60
 
1.9 INFERIOR RIB NOTCHING
Unilateral
  • Blalock-Taussig operation
    Subclavian artery occlusion
    Aortic coarctation left subclavian artery or anomalous right subclavian artery
Bilateral
  • Aorta coarctation, occlusion, aortitis
    Subclavian
    • Takayasu disease, atheroma
    Pulmonary oligemia
    • Fallot's tetralogy
    • Pulmonary atresia
    • Stenosis
    Venous
    • SVC, IVC obstruction
    Shunts
    • Intercostal-pulmonary fistula
    • AV fistula
    Others
    • HPT
    • Neurogenic
    • Idiopathic
 
 
Pleural Effusion
U/L, B/L
Biochemical derangement
Consolidation
Transudate
  • Cardiac failure
  • Hepatic failure
  • Nephrotic syndrome
  • Meigs’ syndrome
B/L
B/L
B/L
U/L
+
+
+
61
Exudate
  • Infection
  • Malignancy
  • Pulmonary infarction
  • Collagen vascular
  • disease
  • Subphrenic
  • Abscess
  • Pancreatitis
U/L, B/L
U/L, B/L
U/L
U/L
U/L
+
+
+
+
+
Hemorrhagic
  • CA bronchus
  • Trauma
  • Pulmonary infarction
  • Bleeding disorders
U/L, B/L
U/L
+/−
+
Chylous
  • Obstructive thoracic duct
 
Small Hilum
Apparent rotation, scoliosis
Vol. loss
Soft tissue
Consolidation
Unilateral
Normal or left side
Lobar collapse, lobectomy
+
Hypoplastic pulmonary artery
+
Macleod's syndrome
+
Unilateral pulmonary embolus
Bilateral
Cyanotic congenital heart disease
Central pulmonary embolus
+
62
 
1.10 ELEVATION OF DIAPHRAGM
 
 
Unilateral
  • Causes above the diaphragm
    • Phrenic nerve palsy
    • Pulmonary collapse
    • Pulmonary infarction
    • Pleural disease
    • Hemiplegia
      • Diaphragmatic cause
    • Eventration
      • Causes below the diaphragm
    • Gaseous distension of stomach/splenic flexure
    • Subphrenic inflammation of diaphragm
    • Scoliosis
    • Decubitus
 
Bilateral
  • Poor inspiratory effort
  • Obesity
    Above the diaphragm
    • B/L basal pulmonary collapse
    • Small lungs
    Below the diaphragm
    • Ascites
    • Pregnancy
    • Pneumoperitoneum
    • Hepatosplenomegaly
    • Intra-abdominal tumor
    • B/L subphrenic abscess
      63
 
Unilaterally Elevated Diaphragm
Phrenic nerve palsy: Smooth hemidiaphragm, no movement on respiration. Paradoxical movement on snuffing.
Pleural disease: Especially old pleural disease, e.g. Hemo-thorax, empyema, tuberculosis, thoracotomy.
Splinting of the diaphragm: Associated with rib fracture or pleurisy due to any cause.
Hemiplegia: Associated with an upper motor neuron lesion.
Eventration: More common on the left side.
Heart is shifted to the contralateral side.
Paradoxical movement on snuffing.
Gaseous distension of stomach or splenic flexure: Only the left hemidiaphragm.
Subphrenic inflammatory disease: Subdiaphragmatic abscess or infection, inflammation
Scoliosis: Raised hemidiaphragm on the side of the concavity.
Decubitus: Raised hemidiaphragm is on the dependent side.
 
Bilaterally Elevated Diaphragm
  • Bilateral basal pulmonary collapse: Which may be secondary to infarction or subphrenic abscess.
  • Small lung due to fibrotic lung disease.
  • Hepatosplenomegaly in patients of lymphoma, anemia and many infectious pathologies.
  • Large intra-abdominal tumors either located in the midline or in any of the superior abdominal quadrant. Ascites in ovarian tumor can also cause this.
 
Pneumothorax
  • Spontaneous
  • Iatrogenic
    64
  • Traumatic
  • Sec to mediastinal emphysema
  • Sec to lung disease
    • Emphysema
    • Honeycomb lung
    • Pneumonia
    • Bronchopleural fistula
  • Pneumoperitoneum
 
Pneumomediastinal
  • Lung tear
  • Perforation of esophagus, trachea, bronchus, perforation of hollow viscera
Pleural calcification
Local pleural mass
Old empyema
Loculated pleural effusion
Old hemothorax
Metastasis
Asbestosis inhalation
Malignant mesothelioma
Silicosis
Pleural fibroma
Talc exposure
 
1.11 PNEUMOMEDIASTINUM
May be associated with pneumothorax and subcutaneous emphysema.
  1. Lung tear: A sudden rise in the intra-alveolar pressure, often with airway narrowing, causes air to dissect through the interstitium to the hilum and then to the mediastinum.
    • Spontaneous: Following severe bout of cough or a severe strenous exercise.
    • Asthma: Usually not before 2 years of age.
      65
    • Diabetic ketoacidosis: Secondary to severe and protracted vomiting.
    • Childbirth—due to repeated Valsalva maneuvers
    • Artificial respiration
    • Chest trauma
    • Foreign body aspiration.
  2. Perforation of esophagus, trachea or bronchus:
    • Spontaneous
    • Boerhaave's syndrome
    • Following severe and protracted vomiting
    • Trauma
    • Foreign body aspiration or inhalation
    Ruptured esophagus also produces left sided pneumo-thorax, hydropneumothorax.
  3. Perforation of a hollow abdominal viscus with extension of gas via the retroperitoneum.
 
 
Right Sided Diaphragmatic Humps
 
At any site
  • Collapse/consolidation of the adjacent lung
  • Localized eventration
  • Loculated effusion
  • Subphrenic abscess
  • Hepatic abscess
  • Hydatid cyst
  • Hepatic metastasis.
 
Medially
  • Pericardial fat pad
  • Aortic aneurysm.
  • Pleuropericardial cyst
  • Sequestrated segment
    66
 
Anteriorly
  • Morgagni's hernia
 
Posteriorly
  • Bochdalek hernia.
 
1.12 LUNG TUMORS
Carcinoma: Approximately 50% of lung cancers arise centrally, i.e. in or proximal to segmental bronchi.
  • Obstruction of lumen leads to collapse and often infection.
  • Peripheral tumors appear as soft tissue nodules or irre-gular masses and invade the adjacent tissues. Signs of collapse and consolidation may occur.
  • Peripheral tumors may arise in the scar. These mass les-ions may present as hilar enlargement, airway obstruction, peripheral mass lesion, mediastinal involvement, pleural and bone involvement.
    Alveolar cell CA: Arises more peripherally, probably from the type II pneumocysts. It arises within the alveoli and produces areas of consolidation.
 
 
Metastasis
  • Hematogenous: Breast, skeleton, urogenital
  • Lymphatic: Less common, breast
  • Endobronchial spread: Alveolar cell carcinoma
Metastasis is usually bilateral, affecting both lung equally, with basal predominance. They are often peripheral and may be subpleural.67
 
Cavitatory Met
  • Squamous cell CA
  • Sarcoma
 
Calcifying Met
  • Osteogenic sarcoma
  • Chondrosarcoma
  • Mucinous adenocarcinoma
 
Endobronchial Met
  • Carcinoma kidney, breast
  • Large bowel.
 
Lymphangitis Carcinoma
Commonest sites—Lung, breast, stomach pancreas, cervix, prostate.
It is usually bilateral, but lung and breast cancers may cause unilateral lymphangitis.
 
Hodgkin's/Non-Hodgkin's Lymphoma
Present as nodal enlargement, which is usually bilateral, asymmetric and involves anterior mediastinal glands. These may calcify following therapy. Pulmonary infiltration may appear as areas of consolidation or areas of miliary nodules. Pleural effusion may be present in 30% of cases.
 
Leukemia
Mediastinal lymph node enlargement and pleural effusion are the commonest radiologic abnormalities.
 
Sarcoma
Kaposi's sarcoma may appear as segmental or lobar consoli-dation.68
Other primary pulmonary sarcomas include fibrosarcoma, leiomyosarcoma—which appear as solitary pulmonary masses, radiographically indistinguishable from a carcinoma of the lung.
 
Adenoma
Carcinoid account for approximately 90% of bronchial adenomas and adenoid cystic tumors for about 10%. These appear as well-circumscribed round or ovoid solitary nodules. On CT, calcification may be seen within the tumor.
 
Hamartoma
They are seen in childhood as solitary pulmonary nodule. Thirty percent of these show calcification, often with a characteristic ‘popcorn’ appearance.
 
Lung Abscess
Radiographically, an abscess may or may not be surrounded by consolidation. Appearance of an air-fluid level indicates that a communication with the airway has developed. It show thick irregular wall, which shows postcontrast enhancement.
 
Bronchiectasis
It is the irreversible dilatation of one or more bronchi and is usually the result of severe, recurrent and chronic infection. It is frequently basal but in tuberculosis and cystic fibrosis, it usually involve the upper zone. Dilated bronchi produce tramline shadows or ring shadows, and dilated, fluid filled bronchi may cause ‘gloved friger’ shadows.69
 
Asthma
During an attack, the chest X-ray may show signs of hyperinflation, with the depression of the diaphragm and expansion of the retrosternal air space. The peripheral pulmonary vessels appear normal, but if the central pulmonary arteries are enlarged, the irreversible pulmonary arterial hypertension is probably present.
 
Chronic Bronchitis
Fifty percent of these patients may have normal chest X-ray. In patients, with a plain film abnormality, the signs are due to emphysema, superimposed infection or possibly bronchiec-tasis. ‘Dirty chest’ appearance is seen.
 
Emphysema
With emphysema, air trapping is present, the lung volumes increase, the diaphragm become flattened, and the retro- sternal air space increases. The no. and size of the peripheral vessels decreases. Central pulmonary arteries may enlarge s/o corpulmonale.
 
Bronchiolitis
Results due to infection (often in childhood) or due to inhalation of toxic fumer, drug therapy and rheumatoid disease. Radiologically, the appearance are most frequently of hyperinflation of lungs and perihilar prominence and indis-tinctness.70
 
1.13 HILAR ENLARGEMENT
 
 
Unilateral
Egg shell calcification
Air bronchogram
LN
Angio
Lymph Node
  • Carcinoma
+
  • Lymphoma
+
+
  • Infective
  • TB
+
  • Histoplasmosis
+
  • Coccidioidomycosis
+
  • Sarcoidosis
+
+
Pulmonary Artery
  • Poststenotic dilatation
+
  • Pulmonary embolus
+
  • Aneurysm
+
+
  • Mediastinal mass— superimposed on a hilum
  • Perihilar pneumonia
+
+/−
 
Bilateral
Symmetrical
Occupational
Lobulated
Idiopathic
+
+
  • Sarcoidosis
Neoplastic
  • Lymphoma
+
  • Lymphangitis carcinomatosis
Infective
  • Viruses
  • Primary TB
+/−
+
  • Histoplasmosis
  • Coccidioidomycosis
71
Vascular
  • Pulmonary arterial hypertension
Immunological
  • Extrinsic allergic alveolitis
+
Inhalation
  • Silicosis
  • Berylliosis
+
 
Unilateral Hilar Enlargement
Carcinoma bronchus
:
The hilar enlargement may be due to the tumor itself or due to the involved lymph nodes.
Lymphoma
:
Unilateral is very unusual.
:
Anterior mediastinal nodes are also involved.
Infective
:
Due to the nodal enlargement
Poststenotic dilatation of the pulmonary artery
:
Usually on the left side.
Pulmonary embolus
:
Peripheral oligemia is characteristic
Aneurysm
:
In chronic pulmonary arterial hyper- tension. Calcification may also be present.
Mediastinal mass
:
Middle mediastinum masses may superimpose.
Perihilar pneumonia, ill-defined borders with presence of air bronchogram.
 
Bilateral Hilar Enlargement
Sarcoidosis
:
Symmetrical, lobulated. Associated bronchotracheal and paratracheal lymphadenopathy.
72
Lymphoma
:
Asymmetrical, but multiple sites
Infective
:
Viral mainly is children
TB - B/L is rare
Histoplasmosis pulmonary nodules (multiple) accompany.
Pulmonary arterial hypertension
:
B/L is rare
Peripheral oligemia is characteristic
Silicosis
:
Symmetrical
Pin point multiple pulmonary nodules are present.
 
Apical Shadows
U/L, B/L
Ellis curve
Pleural outline seen
Rib destruction
Symmetry
Pleural caps
U/L
+/−
Pleural fluid
U/L or B/L
+
+/−
Bullae
U/L
+
Pancoast tumor
U/L
+
Infections – TB
U/L or B/L
Pneumothorax
U/L
+
Soft tissue
B/L
+
+
 
1.14 CALCIFICATION ON CHEST RADIOGRAPH
 
 
Intrapulmonary
Granuloma, infection
Chronic abscess
Tumor
-Metastases
Hamartoma
AVM
Hematoma
Infarct
Broncholith
Alveolar microlithiasis
Idiopathic
73
 
Lymph Nodes
TB, histoplasmosis, sarcoidosis, silicosis
 
Pleural
TB, asbestosis, talcosis
Hemothorax, empyema
 
Mediastinal
Cardiac
Vascular
Tumors
 
Pulmonary Artery
Hypertension
Aneurysm
Thrombus
 
Chest Wall
Costal cartilage
Breast
Bone tumor, callus
Soft tissues74
 
1.15 AIR-FLUID LEVELS ON CHEST X-RAY
Intrapulmonary
  • Hydropneumothorax
Trauma
Bronchopleural fistula
  • Esophageal
Pharyngeal pouch, diverticula Obstruction – tumor, achalasia esophagectomy
  • Mediastinal
Infections
Perforation – esophageal
Pneumopericardium
Diagnostic, trauma
Chest wall
Infection
Diaphragm
Hernia, eventration, rupture
 
 
Cresent Sign
  • Fungal ball
  • Blood clot in tubercular cavity
  • Bronchial adenoma, carcinoma
  • Hamartoma
  • Hydatid cyst
  • Pulmonary infarct.
 
1.16A CAVITATING PULMONARY LESIONS
 
 
Infection
  • Staphylococcus
  • Klebsiella
  • Tuberculosis
  • Histoplasmosis
  • Amebic
  • Hydatid
  • Fungal
    75
 
Malignant
  • Primary
  • Secondary
  • Lymphoma
 
Abscess
  • Blood borne
  • Aspiration
Pulmonary infarct
Pulmonary hematoma
Pneumoconiosis
 
Collagen Diseases
  • Rheumatoid nodules
  • Wegener's granulomatosis
 
Developmental
  • Sequestrated segment
  • Bronchogenic cyst
  • Congenital cystic adenomatoid malformation
Sarcoidosis
Bullae, blebs
Pneumatocele
Traumatic lung cyst
 
1.16B MASS WITHIN CAVITY
  1. Mycetoma - Aspergilloma
  2. Tissue fragment from carcinoma
  3. Necrotic lung within abscess
    76
  4. Disintegrating hydatid cyst
  5. Intracavitatory blood clot.
1
2
3
4
5
• Thick, irregular walled cavity
+
+
+
+
• Adjacent lung parenchymal reaction
+
+/−
+
+/−
+/−
• Clinical history
of infection
of wt. loss
Infection
Infection
+/−
• Mobile
+
+/−
+/−
+
+
• Contrast enhancement in CT of mass
+
+
+/−
• Calcification
+/−
+/− if chronic.
 
1.17 CAVITATING PULMONARY LESIONS
 
 
Causes
  • Malignant
    • Primary
    • Secondary
    • Lymphoma
  • Infections
    • Tuberculosis
    • Staphylococcus
    • Klebsiella
    • Amebic
    • Hydatid
    • Fungal
      77
  • Abscess
    • Aspiration
    • Blood borne
  • Pulmonary infarct
  • Hematoma
  • Pneumoconiosis
    • Pulmonary massive fibrosis
    • Rheumatoid nodular
    • Collagen diseases
    • Wegener's granulomatosis
  • Developmental
    Sequestration
    Bronchogenic cyst
    Congenital cystic adenomatoid malformation
  • Sarcoidosis
  • Bullae, blebs
  • Traumatic lung cyst
  • Pneumatocele
 
Carcinoma
 
Primary
Very frequently cavity nodules turn out to be malignant.
 
Mechanism
Obstruction of an artery
(Infection of a nodule)
  • In 2–10%, especially peripheral upper lobe involvement
  • Most cavities are thick-walled, irregular inner surface
  • Thickness > 15 mm – 85–90% malignant
  • Cavitation—Centric or eccentric
  • Multiple cavitation
  • More common in squamous cell carcinoma and then may be thin-walled.
    78
 
Metastasis—Cavitation less than
  • More common in upper lobe, may involve few nodules
  • Thin or thick-walled
  • Seen especially in squamous cell carcinoma—head and neck
    (Uncommon in adenocarcinoma—esp colon)
    Sarcoma—osteosarcoma
 
Hodgkin's Disease
  • Thick or thin-walled
  • Typically in an area of infiltration
  • Hilar or mediastinal LN
 
Tuberculosis
  • Thick-walled and smooth, sometimes fluid level
  • Mainly affects upper lobes and apical segment of lower lobe
  • Usually surrounded by consolidation and fibrosis
  • Typical there is large cavity surrounded by smaller satellite cavities
  • Cavity walls are lined by tuberculous granulation tissue
  • Cavities traversed by fibrotic remnants of bronchi and vessels
  • Rasmussen aneurysm
 
Staphylococcus Aureus
  • Mostly children, multiple
  • Thick-walled cavities with a ragged inner lining
  • No lobar predilection
  • Associated with effusion and empyema
    79
 
Hydatid Cysts
  • Complicated hydatid cyst
  • Rupture into a bronchus-air cresent sign/air cap
  • Water lily sign
 
Aspergillosis
  • Any pulmonary cavity—TB, histoplasmosis, sarcoidosis
  • Forms a ball which changes position, ball is seen to be mobile
  • Almost always pleural thickening related to mycetoma
  • Vascular granular tissue-bleeding may occur.
 
Abscess (Aspiration)
  • Multiple or single
  • Usually thick-walled
  • Following aspiration
  • Postsegment or apical segment-UL
  • In sitting-right lower lobe
 
Pulmonary Infarct
 
(Infection—may be)
Primarily–
  1. Septic embolus
Secondary to–
  1. Initially sterile, infarct, infection
Tertiary to–
  1. As aseptic cavitating infarct infected
Aseptic cavitation is usually solitary and arises in a large area of consolidation after about 2 weeks.
  • Cavity has scalloped inner margins and cross cavity band shadows/effusion.
    80
 
Cystic Bronchiectasis
  • Thin- walled. Lower lobes
  • Air-fluid levels, peribronchial thickening and retained secretions
  • Crowded vessels and retained secretions
 
Sequestered Lung
  • Thin- or thick-walled
  • 66% in left lower lobe, 33% in right lower lobe
  • Air-fluid level, surrounding pneumonia
 
Wegener's Granulomatosis
  • B/L and widely spread
  • Nodules, cavitation in some nodules (1/3rd)
  • Cavities are thick-walled, shaggy/irregular lining
  • Become thinner with time
  • After therapy may disappear
 
Rheumatoid Nodules
  • Thick-walled with a smooth inner lining and well-defined
  • Lower lobes and peripherally
  • Become thinner with time
 
Progressive Massive Fibrosis
  • Predominantly in mid and upper zone
  • Begin peripherally and move centrally
  • Nodule formation which cavitate into thick and irregular walled cavities in a background nodularity of pneumo-coniosis.
 
Sarcoidosis
  • In early disease, necrosis of coalescent granuloma and check valve mechanism beyond partial obstruction
    81
  • Thin-walled cavities
  • B/L hilar lymph nodes
 
Infected Emphysematous Bullae
  • Thin-walled, air-fluid level
  • Usually seen in emphysema particularly paraseptal and scar associated
  • Apical asymptomatic and those associated with scarring (throughout the lungs-COPD)
  • Associated changes of inflammation in surrounding lung
 
TRAUMA
 
Hematoma—peripheral
  • Air-fluid level—communication with bronchus
 
Traumatic Lung Cyst
  • Single or multiple
  • Peripheral and thin-walled
  • Uni- or multilocular
  • Within hours of injury
 
Bronchogenic Cyst
  • Medial 1/3 of lower lobes
  • If ruptures into a bronchus, thin-walled, air-fluid level and surrounding pneumonia
 
Cystic Adenomatoid Malformation
  • Causes neonatal respiratory distress.
  • Cavities of various shapes and sizes scattered in an area of opaque lung with well-defined margins.
    82
zoom view
Flow Chart 1.17.1:
83
 
1.18A LUCENT LUNG LESIONS
 
MULTIPLE LUCENT LUNG LESIONS
 
Cavities
 
Infection
Bacterial pneumonia
Granulomatous infection
Parasites
 
Neoplasm
 
Vascular
Wegener granulomatosis
Rheumatoid arthritis
Thromboembolic or septic infarct
  • Cystic fibrosis
  • Tuberculosis
  • ABPA
  • Rec. bacterial pneumonia
 
Cysts
Cystic bronchiectasis
Pneumatocele
Congenital lesions—multiple bronchogenic cysts
  • Intralobar sequestration
  • CCAM Type I
  • Diaphragmatic hernia
Centrilobar emphysema
Honeycomb lung disease84
 
Differential Features are same as Localized Lucent Defects
Cyst
Cavity
Thin-walled
Thick-walled > 1 cm
Clear, smooth
Irregular, ragged wall
Well-defined wall
Adjacent lung parenchyma
May show reactive changes
+/−
+/−
Air-fluid level +/−
 
Localized Lucent Defect
Infection
Location
Air- fluid level
Cong/acq.
Uni/multicystic
Specific points
Bacterial
Any zone
+
Acquired
Multi cystic with areas of break-down
Granulomat-tous
Apical
+
-do-
+ve
Fibrosis and cavitating
Fungal
Less likely
Fungal ball
-do-
uni
To be apical
Sarcoidosis
Upper zone
-do-
B/L hilar and R para- tracheal LNs
85
Cystic bron-chiectasis
Lower lobes
Air-fluid level
Cong./ Acquired
+
Pneumato-cele
In area of
+/−
Acquired
+
Staph. infection
Previous pneumonia/post trau-matic hema-toma
Sequela
Intralobar sequestration
Lower lobes
+/−
Cong.
+
Vascular Drain-age is altered
Honeycomb
Lung
Any zone
Acq./End state disease
+
CCAM
+/−
Cong.
Multi-cystic
Cartilage Deve-lopment is defective
 
1.18B SOLITARY PULMONARY NODULE
Malignant
Primary
Secondary
Lymphoma
Plasmacytoma
Alveolar cell carcinoma
Benign
Hamartoma
Adenoma
Connective tissue tumor
86
Granuloma
Tuberculosis
Histoplasmosis
Sarcoidosis
Infection
Round pneumonia
Abscess
Hydatid
Amebic
Fungal
Pulmonary infarct
Pulmonary hematoma
Collagen disease
Rheumatoid arthritis
Wegener's granulomatosis
Congenital
Bronchogenic cyst
Sequestration segment
Cong. bronchial atresia
AVM
Impacted mucus
Amyloidosis
Intraparenchymal lymph node
Pleural
Fibroma
Tumor
Loculated fluid
Nonpulmonary
Skin and chest wall lesions
Artefacts
 
1.19 SOLITARY PULMONARY NODULE
 
 
Definition
Single round intraparenchymal opacity, at least moderately well-marginated and no greater than 3 cm in maximum diameter.87
 
Neoplasm
Benign – Hamartoma, inflammatory pseudotumor
Malignant-Bronchogenic carcinoma, carcinoid tumor, metastasis.
 
Infection
Granuloma—Tuberculoma
Fungal—Histoplasmoma
Abscess
Round pneumonia
Parasites—Echinococcus
 
Inflammatory
Connective tissue-Wegener's granulomatosis
Rheumatoid nodule
Sarcoidosis (Rare)
 
Vascular
Arteriovenous malformation
Hematoma
Pulmonary infarct
Pulmonary artery aneurysm
 
Airway
Congenital lesion-Bronchogenic cyst
Mucocele
Infected bulla
Pseudonodules
  • ECG pads
    Cutaneous lesions
    Mole88
    Nipple shadow
    Hemangiomas
    Neurofibromas
    Lipomas
 
Characteristics of SPN
  1. Size
    • No size criteria that clearly distinguishes benign from malignant SPN
    • 80% of benign SPN <2 cm in diameter
    • 15% of malignant SPN <1 cm in diameter.
    • 42% of malignant SPN <2 cm in diameter.
  2. Growth
    • Benign lesions - <30 days or <450 days (doubling time) SPN with doubling time between 30–450 days require further evaluation
    • Doubling time for spherical lesions is defined as 25% increase in diameter.
  3. Calcification
    • Approximately 1/3rd of non calcified SPN's have calcification on CT
    • Complete/central/laminated: Granulomas
      Popcorn : Hamartoma
      Amorphous/Eccentric calcification : Malignancy.
  4. Fat
    Fat within a smooth/lobulated SPN is suspected benignity of hamartoma – 50% show presence of fat.
  5. Cavitation
    Cavity with greatest wall thickness <5mm are benign >15 mm are malignant
  6. Air bronchogram/bubbly lucencies
    Presence of air bronchogram within SPN is s/o adeno-carcinoma particularly bronchoalveolar cell Ca.89
    Other causes – Lymphoma, organizing pneumonia, pulmonary infarcts and mass like sarcoidosis.
  7. Margins
    • Smooth, well-defined margins s/o benign nodule although 21% of malignant nodules smooth margin.
    • Lobulated / ill-defined / spiculated s/o malignant nodule 25% of benign nodules may have undefined margins.
    • Presence of a small satellite nodule surrounding the periphery of a smooth SPN is s/o granulomatosis infection.
 
CT Nodule Enhancement
  • Enhancement <15 HU s/o benign nodule.
    False +ve : Central necrosis, mucin producing malignant neoplasm
  • Enhancement > 15 HU-Non-specific.
 
Pulmonary Hamartomas
Consist of masses of cartilage with clefts lined by bronchial epithelium which may contain large calcification (popcorn) of fat; Age group : 45–50 yrs
Triad: * Pulmonary chondromas
(Carney's triad): Gastric epitheloid leiomyosarcomas
  • Functioning extra adrenal paragangliomas 90% peripheral and 10% within a major bronchus.
  • Spherical lobulated SPN with popcorn calcification, size <4 cm, fat density positive.
 
Inflammatory Pseudotumor (Plasma Cell Granuloma)
  • Caused histology by mixture of fibroblasts, histiocytes, lymphocytes and plasma cells.
    90
  • Age range is wide and includes children.
  • SPN (2–5cm) or as an area of consolidation, calcification is occasionally present.
Endobronchial tumor can cause obstructive pneumonitis.
 
Bronchial Carcinoid
Bronchial carcinoids can invade locally, may metastasize to hilar and mediastinal lymph nodes as well as to brain, liver and bone.
Age: Age range is wide; Peak-5 decade.
Clinical features-Wheeze, Cushing's syndrome (ectopic ACTH secretion) Carcinoid syndrome
Hilar / parahilar mass
80–90% Central (endobronchial)
10–20% Peripheral with feature of bronchial obstruction, pneumonia, Calcification +/−.
Spherical/lobular SPN (2–4 cm) smooth well-defined margin calcification +/−
 
Bronchial Carcinoma
Sq Cell Ca (30–50%)
Adeno Ca (30–50%)
Undefined Small cell Ca (20–30%)
Large cell Ca (10–15%)
Peak incidence: 50 to 60 yrs
Radiological features: Size > 2cm
Undefined margins
Umbilicated/notched margin
Corona radiata / speculations (+)
Pleural tail sign (+)
Doubling time between 30 to 450 days
Lesion crosses fissure91
Cavitation: (>15 mm thick wall)
Calcification rare if present-eccentric
Associated findings—Hilar/mediastinal lymph nodes, bony mets, pleural effusion, visceral mets (+)
Bronchoalveolar Carcinoma: Air bronchogram/bobby lucencies
Grows slowly
Cavitation is unusual.
 
Metastasis
Pulmonary metastasis is usually from breast, GI tract, kidney, testes, head and neck tumors or from a bone and soft tissue sarcomas.
Site: Usually in the outer portions of lung.
Radiological features (R/f) Solitary/multiple
Spherical well-defined, occasionally irregular edge.
Calcification—unusual except-mets from osteosarcoma, chondrosarcoma
Rate of growth: variable-explosive in choriocarcinoma and osteosarcoma.
Cavitation-unusual (sq cell Ca+).
 
Tuberculoma
  • Occurs in the setting of primary or postprimary TB and is considered to represent localized parenchymal diseases that alternatively activates and heals.
    Nodule is 10–15 mm in diameter.
    Situated most commonly in the right upper zone.
    Single or multiple (confined to a single segment)
    Margins well-defined
    Satellite lesions(+)
    Calcification frequent
    Cavitation +/−
    92
 
Hydatid Cyst
Caused by tapeworm (E. granulosus or E.alveolaris)
Humans are accidental host.
Infection occurs by ingestion of ova by fomites/contami-nated water.
R/F Unruptured cyst: Homogenous spherical/oval, well-defined lesion. Size 1 to 10 cm occurs particularly in middle zone/lower zone.
Ruptured cyst: Usually associated with secondary infection
  1. Meniscus sign-Pericyst–ruptures ecto and endocyst intact appearance is that of an intracavitary body.
  2. Disruption of inner layers.
    1. Air-fluid level
    2. Floating membranes (water lily, camalote sign)
    3. Double wall appearance
    4. Dry cyst with crumpled membranes lying at its bottom (rising sun, serpent sign)
    5. Cyst with all its content expectorated (empty cyst sign).
 
Histoplasmoma
Caused by histoplasma capsulatum which is a fungus found in moist soil and in bird or bat excreta.
Histoplasma represents a small necrotic focus of infection surrounded by a massive fibrous capsule consisting of concentric lamination, some or all of which may calcify.
Sharply defined nodular shadow
<3 cm in diameter
Most common site is in the lower lobe
Satellite lesions (+)
Calcification (+) central/eccentric93
Target lesion is pathognomic—Homogenous density with central punctate deposit of calcium.
Associated findings – Calcified hilar/mediastinal lymph nodes.
 
Pneumonia
Round pneumonias are usually pneumococcal which are usually seen in children, air bronchogram.
 
Lung Abscess
Cavitation secondary to necrosis is seen in
Bacterial pneumoniasStaphylococcus aureus
Gram negative bacteria—Klebsiella pneumoniae, Proteus pseudomonas
Anaerobes
Amebic and fungal infection.
 
Cavitary Lesion with Adjacent Consolidation
Size-2 to 12 cm
Wall thickness < 15 mm
Inner aspect of cavity is smooth.
 
Wegener's Granulomatosis
  • Necrotizing granulomatous vasculitis
  • Lungs involved in 95% cases and late renal involvement is seen in 85% cases
  • Men>Women
    Single/multiple nodules
    Size = 1 cm to several cm
    Well-defined margins
    Wax and wane
    Frequently cavitate94
    Associated findings—Granulomas in upper respiratory tract and glomerulonephritis.
 
Rheumatoid Nodules
Pleuropulmonary is seen in 5 to 54% cases of rheumatoid arthritis.
Pulmonary, necrobiotic nodules are uncommon features of rheumatoid arthritis.
Associated with subcutaneous nodules.
Single/multiple
Variable in size
Wax and wane in size
Cavitation (+) / (−) more common in lower lobe and in periphery.
Similar nodule may be seen in patients of rheumatoid arthritis who have been exposed to silica. Known as Caplan's syndrome.
 
Pulmonary A-V Fistula
Congenital – 50% have hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease).
Acquired – Liver diseases (cirrhosis), schistosomiasis and metastatic thyroid cancer.
Round/lobulated nodule
Prominent adjacent vascular shadow
Most common site—Lower lobe
Variation in size with Valsalva (size)
CT and pulmonary angio shows the feeding artery and vein and vascular nature of nodule.
 
Pulmonary Artery Aneurysm
Most pulmonary artery aneurysms are acquired as a result of 95septic embolization or an extension from a pulmonary paren-chymal calcification.
  • Peripheral aneurysms may mimic a SPN pulsations of mass seen on fluoroscopy.
    Confirmation done by CT or pulmonary angiography.
 
Pulmonary Hematoma
H/o trauma (+); usually appears following resolution of contusion.
Peripheral in location
Smooth and well defined
Slow resolution over several weeks
A pocket of air or fluid level (+).
 
Pulmonary Infarct
  • Becomes visible 12–24 hrs after embolic episode
    Lesions are more frequent in the lower lobe
  • Hump shaped opacity with its base applied to the pleural surface because of partial collapse, hemorrhagic congestion.
  • Cavitation is rare
  • Matched defect is seen on ventricular perfusion scan.
  • Associated pleural effusion (+).
 
Bronchogenic Cyst
  • Peak incidence is in 2nd and 3rd decade.
  • 2/3rd are intrapulmonary and occur in the medial 1/3rd of the lower pulmonary region.
  • Round to oval
  • Smooth-walled and well-defined
    CT shows thin-walled water density cyst.
    96
 
Clinical and Radiographic Criteria for Differentiating Benign and Malignant SPN
Clinical
Benign
Malignant
• Age
<40 yrs except hamartomas
>45 yrs
• Sex
Female
Male
• History
• High incidence of granuloma in area
• Primary lesion elsewhere
• Exposure to TB
• H/o smoking
• Skin test
Positive with specific infectious organism
Negative/positive
Radiographic
Size
Small (< 2 cm)
Large (>2 cm)
• Location
No predilection except for TB
Predominantly on upper lobes except for lung mets
• Definition and contour
Well-defined and smooth
Ill-defined, lobulated umbilicated
• Calcification
Central, laminated Popcorn, complete
Eccentric (very rare)
• Satellite lesion
More common
Less common
• Doubling time
< 30 to >450 days
30 to 450 days
• Presence of fat
(+) S/o hamartoma
97
zoom view
Flow Chart 1.19.1: Investigative algorithm for evaluation of SPN
98
zoom view
Flow Chart 1.19.2:
99
 
1.20 PULMONARY EDEMA ON THE OPPOSITE SIDE TO A PREEXISTING ABNORMALITY
  1. Congenital absence or hypoplasia of a pulmonary artery
  2. Macleod's syndrome
  3. Thromboembolism
  4. Unilateral emphysema
  5. Lobectomy
  6. Pleural disease
(See Table next page)
 
 
Localized Air Space Disease
  • Pneumonia
    Infarction
    Contusion
    Edema
    Radiation
    Alveolar cell CA.
    Differential features are discussed in alveolar shadowing.
 
Unilateral Pulmonary Edema
  • Pulmonary edema on the same side as a preexisting abnormality
    Prolonged lateral decubitus
    Unilateral aspiration
    Pulmonary contusion
    Rapid thoracocentasis of air or fluid
    Bronchial obstruction
    Clinical history is most important in the differential diagnosis of all the above entities.
Bronchial obstruction
  • Respiratory distress +/−
  • e/o occulsion seen in the form of luminal obstruction, atelectasis, fissural displacement.
    100
zoom view
Flow Chart 1.20.1:
101
Location
Duration
Effusion
LNs
Air broncho-gram
Infection
Any
Rapid Resolution
+/−
+/−
Reticulono-dular pattern
Peripheral, central
Hyaline Memb disease
Whole lung
+/−
+
Any
Usually presents with un-usual features
Aspiration
Right UL in Erect
Right LL in Supine
+/−
During resolution
Any
White out lung
Hemo-rrhage/Contusion
Any
Clinical h/o
Alveolar cell
CA
Any
Nonresol-ving
Pneumonia
++
+
Clinical h/o
Lymphoma
Any
+
++
Any
Embolism/infarct
Any
1–2 day posttrauma resolves in 1–4 wks
Any
102
Sarcoidosis
UL
+
Peripheral
Löffler's
UZ
Rapid
Central
Metastasis
Any
No
+/−
+/−
Peripheral
Consolidation
Follow the exposure history
show
+/−
+ in acute-in chronic
P/C
usually from chronic CA
103
 
Alveolar Shadowing
 
Acute
Pulmonary Edema
Cardiac
Noncardiac
  • Hypoproteinemia
  • Fluid overload
  • Drowning
  • Aspiration
  • Inhalation
  • ARDS, uremia
  • Infection
At birth
Aspiration
Hyaline membrane disease
Alveolar
Blood pulmonary hemorrhage
In hematoma
Goodpasture's syndrome
Pulmonary infarction
 
Chronic
Tumors
Alveolar cell carcinoma
Lymphoma
Alveolar proteinosis
Microlithiasis
Radiation pneumonitis
Sarcoidosis
Eosinophilic lung.104
 
Characteristics
4–10 mm diameter
Ill-defined margins
Coalescence
Nonsegmental
 
Air Bronchogram
 
Common
  1. Consolidation pneumonic
  2. Pulmonary edema
  3. Hyaline membrane disease
 
Rare
  1. Lymphoma
  2. Sarcoidosis
  3. Alveolar proteinosis
  4. Alveolar cell carcinoma
  5. Adult respiratory distress syndrome
1
2
3
4
5
6
7
8
Location
Any zone
Peri-hilar
Any zone
Any
UL
Any
Any
Any
Pleural effusion
+/−
+
+/−
+/−
+/−
+
Hilar enlargement
+/−
+
+
+/−
Silhouette with cardiac
+/−
+
+
+/−
+/−
+
Diaphragm
+/−
+
+/−
+/−
+
LNs.
+/−
+
+
+/−
Crazy pavement pattern
+
White out lung.
+
+
Vascular markings visualized
+
+
Resolution
+
+
+
+
+
+
105
 
Mesothelioma
Asymmetrical, irregular
Thickening
Calcification +/−
U/L
 
Pneumonectomy
Rib resection +/−
Thoracoplasty asymmetrical bony contour
H/o present
 
Pulmonary Agenesis
Cong. anomaly
Resp. distress +
Status of diaphragm
 
D/D Diaphragmatic Hernia
N.
–Scaphoid Abd.
Absent
Bowel loops with air +/−
Opaque thorax
A few lucencies +
 
Consolidation
Air bronchogram
Confined to one segment
Air alveologram.
 
Collapse
Vessels not seen
Crowding of fissure and ribs
Hilar and diaphragmatic displacement106
 
Fibrosis
e/o vol. Loss +
 
Cardiomegaly
Cardiac contour conforming of uni/multichamber enlargement.
 
1.21A MILIARY SHADOWING
 
 
D/D Miliary Shadowing
Disseminated pulmonary opacities
  1. Acinar
  2. Interstitial
Acinar—poorly defined, round, parenchymal opacities
  • 4–8 mm in diameter
  • Represent an anatomical acinus filled with fluid.
 
Interstitial
Pulmonary interstitium is a network of connective tissue fibers that supports the lung. It includes alveolar walls, interlobular septa and peribronchovascular interstitium.
Interstitial nodules may take various patterns.
  • Linear and septal lines
    Miliary shadows
    Reticulonodular shadows
    Honeycomb shadows
    Peribronchial cuffing and ground glass pattern.
    Alveolar
    Interstitial
    1. Pluffy ill-defined
    Sharply defined
    2. 4–8 mm
    2–4 mm
    107
    3. Coalescent
    Discrete
    4. Segmental/lober
    Widespread
    5. Air brochogram
    usually 1 week
    6. Time from onset of nodules is a small
    7. Higher density
    Lower density
 
Miliary Shadowing
Is the presence of small, discrete, rounded pulmonary nodules of almost similar size measuring 2–4 mm in the interstitium.
 
Causes
  1. Infectious Diseases
    1. Tuberculosis
    2. Fungal infections—Histoplasmosis, coccidioido-mycosis, blastomycosis
    3. Chickenpox.
  2. Inhalational Disease
    1. Silicosis
    2. Barytosis
    3. Stannosis
    4. Coal miner's pneumoconiosis
    5. Berryliosis
  3. Granulomatous Diseases
    1. Sarcoidosis
    2. Histiocytosis-X
  4. Metastases
  5. Secondary hyperparathyroidism
  6. Oil embolism
  7. Alveolar microlithiasis
    108
  8. Hemosiderosis
  9. Bronchiolitis obliterans
 
Miliary Tuberculosis
  • Due to hematogenous spread of infection
  • May be seen in both primary and post primary disease
  • Small discrete nodules 1–2 mm in diameter, evenly distributed throughout both lungs
  • These are of soft tissue density and are well-defined
  • Other tubercular manifestations as consolidation, pleural effusion, lymphadenopathy may be present.
 
Histoplasmosis
  • Due to infection with histoplasma capsulatum
  • Infection is usually subclinical and heal spontaneously leaving small calcified nodules or calcified mediastinal nodes
  • Infection in immunocompromised may produce multiple nodules scatterred throughout the lung resulting in miliary shadowing.
  • Hilar nodes enlargement is common
  • Consolidation, fibrosis and cavitation may occur.
 
Silicosis
  • Multiple nodular shadows 2–5 mm in diameter
  • Affects mainly mid and upper zones, relatively sparing the bases
  • Hilar adenopathy which may calcify, fibrosis, cavitation may occur.
    109
 
Coal Miner's Pneumoconiosis
  • Small faint, nodules 1–5 mm in diameter appear in mid zone spreading to whole lung
  • Progressive massive fibrosis-mid and upper zones-in complicated cases
  • Emphysematous bullae may appear.
 
Sarcoidosis
  • Multisystem granulomatous disorder affecting young adults
  • 75–90% patients show small, rounded or irregular nodules 2–4 mm in diameter, bilaterally symmetrical with upper and mid zone preponderance
  • Bilateral symmetrical lymphadenopathy, hilar and para-tracheal
  • Air trapping, pleural thickening and effusion may be positive.
 
Histiocytosis X
  • Granulomatous disorder affecting young or middle-aged adults
  • Pulmonary involvement is bilateral symmetrical
  • Chest X-ray shows diffuse nodular pattern in upper and mid zones, 1–5 mm in size. Progress of disease leads to ring shadows, honeycombing and linear shadows.
 
Miliary Metastasis
  • Rare cause of miliary shadowing
    110
  • Primary tumors most likely to provide miliary nodulation are thyroid, renal carcinoma, bone sarcomas and chorio-carcinomas.
 
Hemosiderosis
In patients with heart disease which elevates left atrial pressure, e.g. in mitral stenosis, there is permanent miliary stippling due to focal nature of bleeding.
 
Alveolar Microlithiasis
  • Multiple fine sand like calculi in the alveoli
  • Produce widespread dense opacities on chest X-ray.
  • Clinically there is relative lack of symptoms.
zoom view
Flow Chart 1.21A.1:
111
 
1.21B MILIARY SHADOWING (0.5 TO 2 MM)
Soft tissue densities
Miliary TB
Fungal disease
Pneumoconiosis
Sarcoidosis
Extrinsic allergic alveolitis
Fibrosing alveolitis
 
 
 
Greater than Soft Tissue Density
Hemosiderosis
Silicosis
Siderosis
Stannosis
Barylosis
 
Multiple Opacities (2–5mm)
Remaining discrete
LN
Location
Size
Carcinomatosis
+/−
Any
Variable
Lymphoma
+
Any
Same
Sarcoidosis
+
Mid zone
Variable
Tending to confluence and varying rapidly
Multifocal pneumonia
+/−
Any
Variable
Pulmonary edema
Perihilar
Variable
Extrinsic allergic alveolitis
Basal
Same
Fat emboli
Peripheral
Same
 
Pneumoconiosis
These are diseases caused by inhalation of inorganic dusts. The diagnosis depends on a history of exposure to the dust 112and an abnormal chest radiograph and respiratory function tests.
 
Silicosis
Gold mining, sand blasting, foundry ceramic and pottery workers.
Multiple, nodular shadows 2–5 mm in diameter mid and upper zones.
Linear lines and septal lines may also be seen.
 
Coal Workers
 
Pneumoconiosis
Small, faint, indistinct nodules 1–5 mm in diameter appear in the mid zones.
Coalescence of these nodules is common
Develop bilaterally
Fibrotic masses may calcify.
 
Asbestosis
Asbestosis mining and processing.
In construction and demolition workers ship building.
  • Lower zones nodules
  • Pleural plaque, calcification, diffuse thickening and effusion – mid zone, bilaterally.
  • Pulmonary fibrosis is marked.
  • Initially reticulonodular pattern results – which with progression becomes coarser and there is loss of clarity of the diaphragm and heart.
 
Berylliosis
In acute stage produces noncardiogenic pulmonary edema, while in the chronic stage produces widespread noncavitating granulomas.113
 
1.22 MULTIPLE PIN POINT OPACITIES
  1. Post lymphogram
  2. Silicosis
  3. Stannosis
  4. Barylosis
  5. Alveolar microlithiasis
1
2
3
4
5
At the termination of the thoracic duct
+
In gold miners
+
Inhalation of tin oxide
+
Distribution
Near thoracic duct
Bases and apices spared
Kerley lines
+
Inhalation of barytes
+
Miliary
+
+
+
+
Negative shadows
+
 
 
Septal Lines
Pulmonary edema
Mitral valve disease
Pneumoconiosis
Lymphangitis carcinomatosa
Sarcoidosis
Infection
Lymphoma.
 
1.23 COMPLETE OPAQUE HEMITHORAX
 
 
Causes
Technical
Rotation, scoliosis
114
Pleural
Hydrothorax, lung effusion thickening, mesothelioma
Surgical
Pneumonectomy, thoracoplasty
Congenital
Pulmonary agenesis
Mediastinal
Gross cardiomegaly, tumors
Pulmonary
Collapse, consolidation fibrosis
 
Diaphragmatic Hernia
 
Scoliosis
• Lucency on
• Concave side
• Rotated side
Vertebral anomaly
Clavicular
Asymmetry
 
Effusion
  • Blunted cardiophrenic angle
  • Fluid along the lateral chest wall
  • Silhouette with cardiac and diaphragm
  • Changes with change of posture
  • Thickening
    • Does not follow
      Ellis curve
 
1.24 OPAQUE HEMITHORAX
 
 
Causes
• Technical
Rotation, scoliosis
• Pleural
Pleural effusion
  • Pleural thickening
  • Mesothelioma
• Surgical
Pneumonectomy
  • Thoracoplasty
115
• Congenital
Pulmonary agenesis
• Mediastinal
Gross cardiomegaly, tumors
• Pulmonary
Collapse, consolidation, fibrosis
• Diaphragmatic hernia
 
Rotation
  • In well-centered film medial ends of clavicle are equidistant from spinous process of T4/5 level.
  • Lung nearest to the film, less translucent.
 
Pleural Effusion
  • A massive effusion may cause complete radiopacity of a hemithorax
  • Mediastinal shift to contralateral side
  • Inversion of diaphragm
  • If effusion without mediastinal shift collapse of underlying lung.
 
Exclude Carcinoma Bronchus
  • Ultrasound reveals fluid in pleural cavity. In AP-CXR-with patient supine a small effusion gravitates posteriorly – generalized increased density with apical cap.
    Erect or decubitus film confirms the diagnosis.
    Pulmonary agenesis/aplasia/hypoplasia.
 
Agenesis
  • Complete absence of the lobe as well as its bronchus.
  • Absent vascular supply.
 
Aplasia
  • No lung tissue
  • Rudimentary bronchus
    116
 
Hypoplasia
  • Bronchi and alveoli are present, but the lobe is under-developed.
  • More common on right side.
  • Mediastinal shifts present. Absence of a lobe is more common than absence of whole lung.
  • Loss of silhouette on the right side of the heart and ascending aorta due to deposition of extrapleural alveolar tissue.
  • If whole lung absent—completely opaque hemithorax with mediastinal shift and diaphragmatic shift.
  • Unlike acquired pneumonectomy, gross loss of lung volume, external diameter is not considerable less than normal side in congenital absence.
  • Bronchography—diagnostic.
  • Scintigraphy—absent ventilation and perfusion on affected site.
  • Angiography—absent/hypoplastic pulmonary artery.
 
Diaphragmatic Hernia
  • L > R more common in left side
  • If large hernia in early neonatal period may lead to opaque hemithorax.
  • Bochdalek hernia – posterolaterally due to persistent pleuroperitoneal canal.
    May contain fat, omentum, spleen, kidney, bowel – Asso-ciated with pulmonary hypoplasia and contralateral mediastinal shift.
    • In older age group—hemithorax not opaque due to gas in bowel loops.
      117
 
Consolidation
  • Parenchymal opacification caused by replacement of air in the distal air spaces by fluid (transudates, exudate or blood) or tissue (e.g. bronchoalveolar cell carcinoma, lymphoma) is defined as consolidation.
  • Usually no volume loss
  • Expansile consolidation
    Pneumococcal and Klebsiella pneumonia
    – Neoplasms
    – Air bronchogram
 
Pleural Thickening
If extensive – may lead to opaque hemithorax
  • Previous thoracotomy
  • Empyema
  • Hemithorax
  • Viewed an profile–appears as a band of soft tissue density.
  • An face—ill-defined veil like shadowing
  • USG – not so sensitive pleural thickening not reliably detected unless 1 cm in thickness
  • CT – very sensitive
  • May calcify, involve visceral pleura
  • If entire lung is surrounded by fibrotic pleura – Fibro-thorax
 
Fibrothorax is Defined by Criteria
  • If uninterrupted pleural density that extends over at least a forth of the chest wall
  • On CT - > 8 cm craniocaudal
    • 5 cm laterally
    • 3 mm thick
  • No mediastinal shift
    118
  • Reduced ventilation due to decreased by volume
    If on X-ray—Decreased vascularity, significant ventilatory restriction is present.
    Surgical decortication is required.
 
Mesothelioma
More common primary pleural malignancy
  • Prolonged exposure to asbestos dust – crocidolite (M.C)
  • Nodular pleural thickening ± hemorrhagic pleural effusion around all or part of lung.
With central mediastinum
Volume loss due to ventilatory restriction
Bronchial stenosis by tumor compression at hilum.
Malignant pleural thickening is nodule and extends into fissures or over the mediastinal surface, may surround whole lung.
  • MRI better than CT in assessing involvement of media-stinum and chest wall. Signal intensity slightly more than muscles on both T1 and T2 WI.
 
Postpneumonectomy
  • 2–3 months after surgery
  • H/o of pneumonectomy
  • ± Rib resection
  • ± opaque bronchial sutures.
    119
zoom view
Flow Chart 1.24.1:
120
 
1.25 HYPERTRANSRADIANT LUNG FIELD
 
 
 
Bilateral
  1. Faulty radiologic technique
    • Over penetrated films
  2. Decreased soft tissues
    • Thin body habitus
    • Bilateral mastectomy
  3. Cardiac causes of decreased pulmonary blood flow
    • Right to left shunts (Tetralogy of Fallot, Ebstein's malformation, Tricuspid atresia)
    • Eisenmenger physiology
  4. Pulmonary causes of decreased pulmonary blood flow
    • Pulmonary embolism
    • Air trapping
    • Emphysema
    • Bulla
    • Bleb
    • Interstitial emphysema
 
Unilateral
  1. Faulty radiologic technique
    • Rotation of patient
  2. Chest wall defects
    • Mastectomy
    • Poland syndrome (absence of pectoralis major)
  3. Air trapping
    • Extrinsic compression of main bronchus
    • Endobronchial obstruction
    • Bronchiolitis obliterans
    • Macleod syndrome
      121
    • Emphysema
    • Pneumothorax
  4. Vascular causes
    • Pulmonary arterial hypoplasia
    • Pulmonary embolism
    • Congenital lobar emphysema
    • Compensatory over-aeration
 
Tetralogy of Fallot
  • Congenital disease presenting as left to right shunt with four components VSD, infundibular narrowing of the right ventricular outflow tract, right ventricular hypertrophy, overriding aorta.
 
Plain Skiagram Chest
  • Boot shaped heart
  • Hypoplasia of pulmonary artery
  • Pulmonary oligemia leading to translucent lungs
  • Right sided aortic arch
 
ECHO
  • Discontinuity between anterior aortic wall and IV septum due to overriding aorta
  • Small left atrium
  • RV hypertrophy with small outflow tract
  • Doppler USG can quantify severity of VSD and pulmonary stenosis.
 
Ebstein's Anomaly
  • Congenital disease with left to right shunt with atrialization of right ventricle due to downward displacement of the dysplastic incompetent tricuspid valve leading to a small right ventricle. There is associated ASD or PDA.
    122
  • Patient presents early reversal of the shunt from right to left leading to cyanosis.
 
Plain Skiagram Chest
  • Massive globular “funnel like” cardiomegaly with small pedicle due to hypoplastic aorta and pulmonary trunk (the only CHD with this feature)
  • Extreme RA enlargement
  • Dilated IVC and azygous vein
  • Severe pulmonary oligemia leading to translucent lung fields
  • Calcification of tricuspid valve may occur.
 
ECHO
  • Large sail like tricuspid valve
  • RA enlargement
  • Doppler USG can quantify tricuspid regurgitation.
 
Tricuspid Atresia
  • Congenital disease with atresia of the tricuspid valve and pronounced cyanosis at birth. Associated with ASD and a small VSD. Pulmonary stenosis may or may not be present. May present with or without transposition of great vessels.
 
Plain Skiagram Chest
  • Left ventricular contour of the heart with rounding due to both enlargement and hypertrophy of left ventricle.
  • RA enlargement
  • Concave pulmonary bay
  • Pulmonary oligemia leading to translucent lung fields.
    123
 
Eisenmenger Physiology
  • Occurs when there is reversal of left to right shunt as a consequence of pulmonary arterial hypertension
 
Plain Skiagram Chest
  • Pronounced dilatation of central pulmonary arteries
  • Pruning of peripheral pulmonary arteries leading to increased translucency
  • Enlargement of RV
  • Return of LA and LV to normal size
  • Normal pulmonary venous pressure.
 
Pulmonary Embolism
  • The embolism is usually a result of DVT in the lower limbs
  • There is a classic traid seen in 33% of cases of hemoptysis, pleural rub and thrombophlebitis
  • Hypertranslucency is seen bilaterally in cases presenting with acute massive embolic episode, which blocks the main pulmonary artery before the development of infarction. The development of infarction leads to segmental, lobar or wedge shaped areas of consolidation. Pleural effusion is usually present.
  • Unilateral hypertranslucency may occur in cases where the embolus block one of the major pulmonary artery.
 
Air Trapping
  • There is trapping of air in the lungs due to valve mecha-nism acting at the level of the trachea or major bronchi
  • In children this usually due to a foreign body. In adults an endotracheal or endobronchial growth of extrinsic pressure is the usual cause.
  • On plain skiagram chest there is hypertranslucency with evidence of increased volume like splaying of ribs, long 124tubular heart, barrel-shaped chest due to increase AP diameter of the chest and depressed domes of diaphragm. These findings may be unilateral or bilateral depending on the etiology. However in unilateral increase in volume these findings are unilateral except for the contralateral shift of mediastinum and largely normal cardiac contour.
    Bulla, Blebs and Pneumatoceles: When very large may compress the surrounding normal lung and may lead to either unilateral or bilateral hypertranslucency.
    Bronchiolitis obliterans: Also known as constrictive bronchiolitis or obliterative bronchiolitis is a result of inflammation of bronchioles leading to obstruction of bronchial lumen.
  • Chest X-ray may be normal
  • Hyperinflated lungs leading to increased lucency may be seen in upto 60% of cases
  • There is decrease in pulmonary blood flow
  • On HRCT there is mosaic perfusion and lobular air trapping may be seen, bronchial wall thickening and bronchiec-tasis may also be seen.
Macleod syndrome: Also known as Swyer-James syndrome is result of acute viral bronchiolitis in infancy, leading to constrictive bronchiolitis.
  • There is increased translucency of the affected lung
  • Small hemithorax with decreased or normal volume of the lung
  • Air trapping during expiration
  • Small ipsilateral hilum
  • Reduced pulmonary vasculature with pruning of vessels.
Emphysema: This term is broadly used to define pulmonary diseases characterized by permanently enlarged air spaces distal to terminal bronchioles accompanied by destruction of alveolar walls and local elastic fiber network.125
 
Plain Skiagram Chest
  • Hyperinflated translucent lungs
  • Low or flat hemidiaphragms
  • Increased retrosternal air space
  • Barrel chest
  • Pulmonary vascular pruning
  • Right heart enlargement
  • Bullae
Compensatory Emphysema or over-aeration is a distinct clinical entity where there is unilateral findings of emphysema seen due to diseased nonfunctional contralateral lung.
 
Pneumothorax
  • Can be unilateral or bilateral and is a result of collection of air in the pleural cavity.
 
Plain Skiagram Chest
  • There is increased translucency with loss of broncho- vascular markings
  • There is contralateral shift of mediastinum in the unilateral types
  • In tension pneumothorax there may be inversion of diaphragm.
 
Congenital Lobar Emphysema
  • Result of congenital insult leading to constriction of bronchi supplying one lobe leading to air trapping and increase in volume.
  • The enlarged lobe compresses the remaining normal lobes
  • Contralateral mediastinal shift.
 
Pulmonary Arterial Hypoplasia
  • Small or absent main pulmonary artery
  • Concave pulmonary bay
  • Pulmonary oligemia.
    126
zoom view
Flow Chart 1.25.1:
127
zoom view
Flow Chart 1.25.2:
128
 
1.26 HYPERTRANSLUCENT LUNG FIELD
 
 
Causes of Bilateral Hypertranslucency
 
Faulty Radiologic Technique
  • Over penetrated film
 
Decreased Soft Tissues
  • Thin body habitus
  • Bilateral mastectomy
 
Cardiac Cause
  • Right to left shunt
  • Eisenmengerization of left to right shunt
 
Pulmonary Cause
  • Decreased vascular bed
    • Pulmonary embolus.
  • Increase in air space
    • Air trapping—asthma, acute bronchitis, emphysema
    • Bullae, blebs
    • Interstitial emphysema.
 
Localized Lucent Lung Defect
  • Cavity
    • Infection
    • Neoplasm
    • Vascular occlusion
    • Inhalational – Silicosis with coal worker's pneumo-coniosis.
  • Cyst
    • Cystic bronchiectasis
      129
    • Pneumatocele
    • Centrilobular/bullous emphysema
    • Honeycomb lung
    • Diaphragmatic hernia
    • CCAM Type I, CLE, bronchogenic cyst.
Hyperlucent lung :
(Unilateral)
Normal
Increased density contralateral lung
Over penetrated film
Technical
Over penetrated film
Rotation, scoliosis
Soft tissue
Mastectomy
Cong. Absence of pectoralis major poliomyelitis (Poland's syndrome)
Emphysema
Compensatory: Lobar collapse
Lobectomy
Obstructive : Foreign body, tumor
Macleod's syndrome.
CLE.
Bullous.
Vascular
Absent/hypoplastic pulmonary artery, obstructed pulmonary artery < Tumor embolus
Pneumothorax
Macleod's syndrome.
 
1.27A HONEYCOMB LUNG
Common
Rare
Histiocytosis-X
Tuberous sclerosis
Scleroderma
Amyloidosis
Rheumatoid disease
Neurofibromatosis
Fibrosing alveolitis
Lymphangiomyomatosis
Pneumoconiosis
130
Sarcoidosis
Similar appearance
Bronchiectasis
Connection with bronchus +
Cystic fibrosis
Pancreatic anomalies + Achlorhydria
Location
Upper zones
Extrinsic allergic alveolitis
Upper and midzones bases
Histiocytosis
Rheumatoid
Scleroderma
Cystic bronchiectasis
Cryptogenic fibrosing alveolitis
Mid and bases
Sarcoidosis
 
 
Multiple Pin Point Opacities
Postlymphogram
:
Iodized oil emboli. Contrast medium is seen at the site of termination of the thoracic duct.
Silicosis
:
Located in upper and mid zones, seen in gold miners.
Stannosis
:
Evenly distributed throughout the lung with Kerley A and B lines
Barylosis
:
Inhalation of barytes Very dense, discrete opacities May be slightly larger in size
Bases and apices are spared
Alveolar microlithiasis
:
Familial, black pleura, enlarged heart size is positive.
 
Lobar Pneumonia
Consolidation involving the air spaces of an anatomically recognizable lobe. The entire lobe may not be involved and there may be a degree of associated collapse.131
  1. Streptococcus pneumonia: Commonest cause, unilobar in distribution. No cavitation. Little or no collapse. Pleural effusion is uncommon.
  2. Staphylococcus: Especially in children. Sixty percent develop pneumatocele. No lobar predilection, effusion, empyema and pneumothorax and bronchopleural fistulae are common.
  3. Klebsiella pneumoniae: Multilobar involvement, cavitation and lobar enlargement is common.
  4. Tuberculosis: Associated collapse is common.
    Right lung is more frequently involved.
    Anterior segment of the upper lobe and the medial segment of the middle lobe are the commonest sites.
  5. Streptococcus pyogenes: Lower lobe predominates, often associated with pleural effusion.
 
Consolidation with Bulging Fissures
Homogeneous or inhomogeneous air space opacification with bulging of the bounding fissures.
  1. Infection with abundant exudates
    Klebsiella, Streptococcus pneumoniae, Tubercular bacilli
  2. Abscess: When air-area of consolidation breaks down.
    Common organism include Staph. aureus, klebsiella and other gram −ve organism
  3. CA of the bronchus.
 
LUNG DISEASE ASSOCIATED WITH HONEY COMBING
 
Collagen Disorders
Rheumatoid lung :
Basal predominance
Infiltrates and effusion are common
132
Scleroderma basal
Preceded by fine, linear basal streaks.
Extrinsic allergic alveolitis upper zones
Sarcoidosis sparing of extreme apices
  • Hilar lymph adenopathy
  • Egg shell calcification.
    Pneumoconiosis
    :
    Mainly due to asbestosis
    Cystic bronchiectasis lower and middle zones
    Bronchial wall thickening
    Localized areas of consolidation
    Histiocytosis-mid and upper zones.
Disseminated nodules followed by honeycomb pattern
Tuberous sclerosis :
Rare
Neurofibromatosis :
Rib notching +
Ribbon ribs +
Scoliosis
 
1.27B HONEY COMB PATTERN
  1. A generalized reticular pattern or miliary mottling which when summated produces the appearance of air containing ‘cysts’ 0.5–2 cm in diameter.
  2. Obscured pulmonary vasculature.
  3. Late appearance of radiological signs after the onset of symptoms.
  4. Complications
    1. Pneumothorax is frequent
    2. Cor pulmonale later in the course of the disease.
 
 
Causes
  1. Collagen diseases-Rheumatoid arthritis
    Scleroderma
    133
  2. Extrinsic allergic alveolitis
  3. Sarcoidosis
  4. Pneumoconiosis
  5. Cystic bronchiectasis
  6. Cystic fibrosis
  7. Drugs—nitrofurantion busulfan, cyclophosphamide, bleomycin and melphalan
  8. Langerhans cells histiocytosis
  9. Lymphangio leiomyomatosis
  10. Tuberous sclerosis
  11. Idiopathic interstitial fibrosis (cryptogenic fibrosing alveolitis)
  12. Neurofibromatosis
 
Rheumatoid Arthritis
  • Most pronounced at the bases.
  • It's severity does not parallel to that of joint involvement.
  • In the earlier stages it is characterized by radiologic appearance of patchy area of air space consolidation (multifocal ill-defined densities).
  • In the intermediate stage there are fine reticular pattern or reticulonodular pattern.
  • As the disease progress there is appearance of cystic spaces of honeycomb lung.
  • All the above features may be preceded by basal infil-terate ± small effusion.
 
Scleroderma
  • Predominantly basal
  • Less regular ‘honeycomb’ pattern which is preceded by fine, linear, basal streaks cor pulmonale is unusual.
    134
  • Other clinical signs which include skin changes, soft tissue calcification, disturbances of esophageal motility and dilatation of the esophagus.
  • Radiologically, an upper GIT series may demonstrate.
    Both esophageal dilatation and decreased motility as well as small bowel dilatation.
 
ASBESTOSIS
  • It produces a basilar distribution that may progress from a fine reticular interstitial pattern to a coarse interstitial pattern with honeycombing.
  • The basilar reticular or honeycomb pattern is also fre-quently associated with pleural thickening, pleural calci-fication.
 
Silicosis
  • It has predominant upper lobe distribution.
  • It may be associated with hilar or mediastinal lymphade-nopathy with pleural thickening. The fine reticular pattern is seen which progresses to honeycomb lung.
 
Extrinsic Allergic Alveolitis
  • Predominantly seen in the upper lobes of the lung.
 
Sarcoidosis
Sparing of extreme apices
  • Honeycombing of the lung is usually proceded by some classic finding including hilar adenopathy and an interstitial nodular or fine reticular interstitial pattern.
    135
  • As the interstitial disease progresses there is regression of hilar adenopathy.
 
Langerhans Cell Histiocytosis
  • ‘Honeycomb’ pattern preceded by disseminated nodules.
  • May be predominantly in the mid and upper zones.
  • Cor pulmonale is uncommon.
 
Usual Interstitial Pneumonitis/Cryptogenic Fibrosing
 
Alveolitis
  • More marked in the lower lobes of the lungs initially and progresses to involve the whole of the lungs.
  • In HRCT there is honeycombing and fibrosis. It shows a uniform and patchy distribution.
 
Tuberous Sclerosis
  • Symptoms when they appear, usually first appear in adult life.
  • Pneumothorax, pulmonary insufficiency and cor pulmo-nale may complicate the syndrome.
  • The clinical and radiological manifestation of the disease in the brain, kidneys and skin readily establish the diagnosis.
 
Neurofibromatosis
  • Honeycomb lung ± rib notching ribbon ribs and/or sco-liosis. In 10% but not before adulthood.
    136
zoom view
Flow Chart 1.27B.1:
137
 
1.28 PLEURAL DISEASES
  • Serous membrane which covers the surface of lung and lines the inner surface of chest wall.
Common conditions are:
  • Pleural effusion
  • Pleural thickening
  • Pneumothorax
  • Pleural masses
  • Pleural calcification
 
 
 
Pleural Effusion
May be transudate, exudate, pus, blood or chyle.
 
Transudate
Contain < 3 gm/dl of protein, usually bilateral
  1. Increase hydrostatic pressure
    Main cause is congestive cardiac failure (CCF)—1st on right side and then bilateral, constrictive pericarditis.
  2. Decrease colloidosmotic pressure
    • Decrease protein product—cirrhosis with ascitis
    • Protein loss/hypervolemia
      Nephrotic syndrome
      Overhydration
      Peritoneal dialysis
  3. Meig-Salmon syndrome
    Ovarian fibroma, thecoma, GCT, Brennet T, etc.
    • Ascitis
      Pleural effusion resolve with tumor removal.
 
Exudate
Increased permeability of abnormal pleural capillaries with release of high protein fluid into pleural space.
> 3 gm/dl of protein.138
  1. Infection
    1. Empyema—Pleural effusion with presence of pus. +/− positive culture.
      Microorganism are anaerobic bacteria
      Gross pus (WBC >15000/cm3)
    2. Parapneumonic effusion—Less with pneumonia, abscess, bronchiectasis.
    3. TB—Increase protein content >75 gm/dl
    4. Fungi and parasite—amebiasis, secondary to liver abscess.
  2. Malignant disease- Lung Ca, lymphoma, breast, ovarian Ca and malignant mesothelioma. Positive cytological result.
  3. Vascular—Pulmonary embolism (15–30%)
  4. Abdominal disease
    Pancreatitis-
    Left side pleural effusion (68%), right side (10%).
    Boerhaave's syndrome-
    Left side
    Subphrenic abscess-
    Pleural effusion—79%
    Elevation and restriction of dia-phragmatic movement
    Endometriosis
    Plate-like atelectatic or pneumonia.
  5. Connective tissue disorder.
    RA—UL(R>L) recurrent alternating sides relatively unchanged in size for months.
 
SLE
B/L in 50% (L>R), increase cardiac size.
 
Wegener's Granuloma
 
Hemothorax
Bleeding into the pleural space may be trauma.
Hemophilia or excessive anticoagulation—Rare
Pulmonary infarction – Blood stained
  • Lung carcinoma-blood stained.
    139
 
Chylothorax
Chyle is milky fluid high in neutral fat and fatty acid.
Secondary to damage or obstruction of the thoracic lymphatic vessels
Causes
Most common cause—trauma—surgery.
Carcinoma of lung, lymphoma, filariasis.
 
Radiological Features
Plain film: Frontal view less sensitive < Lateral view < lat. decubitus view.
  • Moderate effusion with mediastinum, is shifted towards the side of collapse-likely due to carcinoma of bronchus.
  • Empyema may be suspected by the appearance of a fluid level.
  • Septations.
 
USG
Very sensitive, can detect few ml of fluid.
Transudate—Clear fluid separating the visceral and parietal pleura
Moving lung suspended within the pleural space.
Exudate—Echogenic fluid, containing floating particulate material, septations or fibrin strands may be associated with pleural nodule or thickening > 3 mm
CT—Simple pleural effusion—Sickle shaped disease in the most dependent part of thorax posteriorly
  • In regard to tissue density—CT is rarely helpful, however
  • Exudate- >water density septation.
  • Parietal pleural thickening on CECT
  • Extrapleural fat thickening of >2 mm
  • Chylous—Decrease density than H2O
    Acute hemorrhage—Increase density of fluid with presence of fluid-fluid level.
    140
 
PLEURAL THICKENING
  • Nonpathological
    B/L apical pleural thickening, symmetrical
    Elderly patient
    Probably ischemia is the cause
  • Trauma: If the entire lung is surrounded by the fibrotic
    Fibrothorax secondary to organized effusion, hemothorax or pyothorax.
  • Dense fibrous layer of 2 cm thickness almost always on visceral pleura.
  • Frequent calcification on inner aspect of pleura.
 
INFECTION
Chronic empyema—H/O pneumonia parenchymal scars. Usually seen over the bases.
Frequently a thickened layer of extrapleural fat can be seen separating the parietal and visceral layer.
Calcification may be seen.
 
 
TB
Lung apex
Can be associated with apical cavity
Calcification may be seen
 
Inhalation Disorder
Asbestos exposure involves the lower lateral chest wall, basilar interstitial disease.
Pleural plaque: Involves the parietal pleura with sparing of visceral pleura.
 
Neoplasm
Asymmetric apical pleural thickening may represent Pancoast tumor destruction of adjacent ribs and spine penetrated film will be helpful.
  • Metastasis—often nodular
    141
 
PLEURAL CALCIFICATION
Has the same causes as pleural thickening.
U/L pleural calcification—result of previous empyema, hemothorax or pleurisy and also occur in visceral pleura associated with pleural thickening.
Calcification may be in a continuous sheet or in discrete plaque.
B/L calcification seen in asbestos exposure, more delicate frequently visible over the diaphragm and adjacent to axilla located in parietal pleura.
 
PLEURAL MASSES
  • Incomplete border and tapered superior and inferior borders.
  • Usually make obtuse angle with chest wall.
  • Displacement of adjacent lung parenchyma with compressive atelectasis and blowing of bronchi and pulmonary vessels around the mass.
  • Vanishing tumor and encysted pleural effusion fluid may become loculated in interlobar fissure seen in heart failure lateral film typical lenticular configuration. Encysted pleural effusion-often associated with free pleural effusion.
  • Water density.
  • Neoplasm.
 
 
Benign
  • Lipoma—CT detect the origin of mass of fat density.
    Benign lipoma confirm fat density with few fibrin strands.
  • Thymolipoma, angiolipoma, teratoma, characterized by islands of soft tissue density, interspersed with fat.
  • Fibroma/benign fibrous mesothelioma—Most common benign tumor may be associated with hypoglycemia and HPOA solitary lobulated non-calcification mass.
    142
    If pedicle is seen—diagnostic, shape change with the change in patient's position.
 
Malignant Pleural Thickening
Bronchogenic Carcinoma: Most common cause.
When a bronchogenic carcinoma involves the pleura diffusely with resultant pleural effusion, the tumor is considered unresectable.
 
Malignant Mesothelioma
  • Rare tumor.
    70% of cases—H/O asbestos exposure
    Nodular pleural thickening around all or part of lung with pleural effusion
    Pleural—plaque
    Metastatic disease—Breast and GIT
    Most common manifestation is malignant pleural effusion.
    Pleural thickening is nodular and frequent. Encase the entire lung including mediastinum.
  • Pleural lymphoma.
  • Pleural effusion.
    CT= localized broad based lymphomatous pleural plaque.
 
PNEUMOTHORAX
Spontaneous—Most common type
M:F: 8:1, young male with tall thin stature
Due to rupture of a congenital pleural bleb such blebs are usually in the lung apex may be B/L.
Iatrogenic— For example postoperative, after chest aspiration during artificial ventilation, after lung biopsy.
Traumatic—result of a penetrating chest wound, closed chest trauma, associated finding like rib fracture.
 
Hemothorax
Surgical/mediastinal emphysema143
Secondary to lung disease—
  • Emphysema
  • Chronic bronchitis
    Common factor in elderly patient
    Rupture of a tension cyst in Staph. pneumoniae
    Rupture of a subpleural TB focus
    Rupture of a cavitating subpleural mets.
    Pneumoperitoneum—air passes through a pleuroperitoneal foramen.
    Generalized
  • Localized—If pl. adhesion are present.
 
Open
If air can move freely in and out of pleural space during respiration.
 
Closed
If no movement.
Valvular: If air enters the pleural space on inspiration but does not leave on expiration it is valvular-as intrapleural pressure increase it leads to development of tension pneumo- thorax.
Radiological features: Small pneumothorax in an erect patient collects at the apex.
Expiratory film—useful in closed pneumothorax.
Lat. decubitus film with affected side uppermost.
Tension Pneumothorax: Massive displacement of media-stinum.
  • Kinking of great veins
  • Acute cardiac and resp. embarrassment.
  • Ipsilateral lung may be squashed against the mediastinum and herniate across the midline.
    144
  • Depression of ipsilateral diaphragm.
Loculated pneumothorax = pleural adhesion may result in loculated pneumothorax.
D/D—subpleural bullae, thin-walled pulmonary cavity/cyst.
Few linear strands can be seen in these but not in pneumothorax.
Hydropneumothorax containing a horizontal fluid level.
(See Flow Chart 1.28.1 Next Page)
 
1.29 PLEURAL FLUID
 
 
Radiological Appearances of Pleural Fluid
  • Most dependent recess of the pleura is the posterior costophrenic angle (100–200 ml of fluid is required to fill this). Small effusions are hence seen earlier on a lateral film and now on ultrasound.
  • Decubitus views with a horizontal beam is the most sensitive view.
  • The effusion casts a homogeneous opacity spread upwards. Typically, this opacity has a fairly well-defined, concave upper edge, which is higher laterally than medially and obscures the diaphragmatic shadow.
  • A massive effusion may cause complete radiopacity of a hemithorax.
  • In the presence of a large effusion, lack of displacement of the mediastinum suggests that the underlying lung is completely collapsed.
  • Lamellar effusion are shadow collection between the lung surface and the visceral pleura.
  • Large effusions may accumulate between the diaphragm and the undersurface of a lung—this is called sub-pulmonary pleural effusion. The apex is more lateral than normal. This collection moves fully with changes of posture.
    145
    zoom view
    Flow Chart 1.28.1:
    146
  • Empyema usually has a lenticular shape, irregular thick walls and may compress the underlying lung.
  • Loculated effusions tend to have comparatively little depth, best considerable width, rather like a biconvex lens.
 
Pneumothorax
It collect in a free pleural space in an erect patient at the apex. On the frontal film, sharp white line of the visceral pleura will be visible, separated from the chest wall by the radiolucent pleural space, which is devoid of lung markings.
An expiratory film will make a closed pneumothorax easier to see since on a full expiration, the lung volume is at its smallest, while the volume of pleural air is unchanged.
In tension pneumothorax, the ipsilateral lung may be squashed against the mediastinum, or herniate across the midline, and the ipsilateral hemidiaphragm may be depressed.
Nodular extension into the fissures, pleural effusion, volume loss of the ipsilateral lung all suggest malignancy.
Metastatic: The most frequent primary tumors being of the bronchus and breast.
 
1.30 PLEURAL TUMORS
Benign:
Mesothelioma: Well-defined, lobulated mass adjacent to chest wall, mediastinum, diaphragm.
Lipoma: Well-defined, lobulated mass may change shape with respiration on CT, presence of fat is diagnostic.
Malignant:
Mesothelioma: Due to prolonged exposure to asbestosis.
Nodular pleural thickening with pleural effusion. Rib involvement may occur but is rare.
147
 
1.31 PLEURAL CALCIFICATION
The common conditions are:
  1. Old empyema
  2. Old hemothorax
  3. Asbestos inhalation
  4. Silicosis
 
 
Old Empyema and Old Hemothorax
  • Calcification is irregular, resembles a plaque or sheet and is contained within thickened pleura.
  • Enface it is hazy and veil like but inprofile it is dense and linear, paralleling the chest wall
  • Usually unilateral
  • Most common site: Lower posterior half of chest
  • In tuberculous empyema—both visceral and parietal pleura may be calcified which are sometimes separated by a soft tissue opacity which may contain fluid.
 
Asbestos Inhalation
Features of asbestosis is pleural plaque which is a well-defined soft tissue sheet orginating in the parietal pleura (latent period is 10 yrs.)
  • Latent period for calcification to develop is 20 yrs.
  • Lesions are usually bilateral, lying in the middle zone, lower zone and diaphragm.
    When calcified – ‘holly leaf pattern’ with sharp and often angulated outlines and often follow the margins of the ribs.
  • Usually <1 cm thick
    Diffuse pleural thickening: Unlike pleural plaques the margins are well-defined and tapered; may reach several cm in thickness.
    Pleural effusion—Uncommon
    148
 
Malignant Mesothelioma
Latent period: 40 yrs
Pulmonary changes : (peripheral lower zone)
  • Fibrosis
  • Bronchial carcinoma
  • Pseudotumor (fibrotic atelectasis)
 
Extrathoracic Manifestation
Peritoneal mesothelioma, malignancy of upper GIT.
 
Silicosis
  • Inhalation of silica (SiO2)
  • Pleural calcification is similar to asbestosis.
 
Other Features
  • Multiple small nodules in upper zone and middle zone.
  • Hilar lymph nodes with egg shell calcification
  • Progressive massive fibrosis
  • Caplan's syndrome also occurs in patients with rheuma-toid arthritis and silicosis.
zoom view
Flow Chart 1.31.1:
149
 
1.32 HIGH RESOLUTION CT-PATTERN OF PARENCHYMAL DISEASE
 
 
Peripheral, Base
  1. Cryptogenic fibrosing alveolites
    Early
    :
    Ground glass appearance Subpleural reticular shadows
    Later
    :
    Reticulations extend centrally
    Chronic
    :
    Small cyst formation, commencing at subpleural site.
  2. Asbestosis
    Early
    :
    Changes are seen at the lung base.
    Posteriorly.
    Thickened curvilinear, subpleural lines are seen.
    Thickened subpleural septal lines, coarse parenchymal lines extending centrally.
    Chronic
    :
    Honey combing
    Rounded atelectasis with comet tail sign.
 
Central Upper Fluid Zones
Sarcoidosis
:
Thickened bronchovascular markings with perivascular beading present centrally.
Patchy alveolar opacification.
Subpleural and peribronchovascular nodules.
 
Peripheral and Central
Lymphangitis:
Bronchovascular markings and septal line thickening.
No alveolar opacification is seen.
150
 
Widespread
Lymphangio-leiomyoma-tosis
:
Characteristic widespread distribution.
More common in women.
Uniform sized well-defined cysts with normal parenchyma surrounding them.
 
Tuberous Sclerosis
Variable sized cyst
No feminine predilection.
 
1.33 CARDIOPHRENIC ANGLE MASS
  1. Solid
    1. Fat Density
      1. Epicardial Fat Pad
        • Obese, Cushing's syndrome
        • Uncapsulated, homogeneous extrapleural fat
      2. Lipoma
        • Uncommon, well-defined, encapsulated thin fibrous septae
      3. Liposarcoma
        • Ill-defined
        • Inhomogeneous
      4. Morgagni hernia
    2. Soft Tissue
      Lymph Nodes
      • Lymphoma
      • Carcinoma—breast, lung, colon
      Traumatic-Diaphragmatic Hernia
      • H/O trauma
      • Mostly left sided
        151
      • Single entry and exit
      • Barium or other studies—useful in diagnosis
      Diaphragmatic Hump
      • Herniation of liver through the gap
      • Liver scan or USG
      Fibrous Tumors of Pleura
      • Pleura based, well-defined, homogeneously enhancing, stalked.
      Primary or Secondary Malignancy
      • Well-defined smoothly marginated lung based.
  2. Cystic or Vascular
    • Pericardial cyst
    • Well-defined, round to oval, fluid density, non- enhancing, right CP angle.
    Hydatid Cyst
    • Unilocular, associated with hepatic cyst or may be bilateral.
    • Meniscus sign, water lily sign.
    • Loculated pleural effusion.
    • USG—makes the diagnosis
    • Varices
    • Delayed phase scanning is needed
    • Portal hypertension, more on right.
    • Scimitar syndrome
    • Abnormal vessel draining into IVC or hepatic vein
    • Lobar agenesis or aplasia
    • Accessory diaphragm, pulmonary sequestration.
    Pericardial Cyst
    • Etiology—embryogenesis, parietal recess, diverticu-lum, sequelae.
    • 30–40 yrs, asymptomatic
    Plain film chest—well-defined, round to oval mass
    • Cardiophrenic angle mass usually right
    • Changes shape with respiration and body position.
      152
 
 
 
US
Well-defined, anechoic to hypoechoic, No septae
 
CT
3–8 cm in size
  • May extend into fissures
  • No enhancement, no perceptible wall
 
Hydatid Cyst
  • Three layers—Adventitia, friable ectocyst, inner germinal layer.
  • Lung cyst—Unilocular, 20% bilateral, 10% associated with hepatic cyst.
  • Well-defined, round-oval, homogenous masses upto 10 cm in diameter.
  • Calcification is rare.
  • Meniscus sign, water lily sign.
 
Morgagni Hernia
  • Defect between septum transversum and right and left costal margins of diaphragm.
  • Usually asymptomatic, more common in obese people.
  • Right sided, small lesions may only have omental fat, then it may be difficult to distinguish from epicardial fat pad.
  • Large lesion—colon, liver, stomach or small intensive may herniate.
    Ba study—tenting of colon or loop above the diaphragm.
    CT—Omental fat, omental vessels and abdominal viscera seen in the mass.
 
Diaphragmatic Hump and Hernia
  • Trauma—Hernia mostly seen on Lt side (post central)
  • Colon or less commonly stomach are the contents.
    153
    Ba—Entry and exit through the defect are closely apposed.
  • Obstruction is frequent probably because of angular margins of the defect but are detected late because of subtle changes in plain film.
    On Rt side—Liver may herniate in severe trauma
  • A liver scan is helpful.
 
Congenital Hernia
More common on right
It has a hernial sac.
 
Scimitar Syndrome
  • Presence of partial anomalous pulmonary venous return below the diaphragm, mostly right side.
  • Lobar agenesis or aplasia, other systemic artery from aorta in lower thorax or upper abdomen.
  • Pulmonary artery may be small or entirely absent, acces-sory diaphragm, hepatic herniation, pulmonary sequestration.
 
Fibrous Tumors of Pleura
  • Solitary, sharply defined, sometimes lobulated soft tissue pleural based mass without evidence chest wall invasion, homogeneous enhancement.
  • Pedicle or stalk—pathognomonic and indicator of benign lesion, mobility.
  • May grow very large than obtuse or acute angle may be formed with pleura.
 
Primary or Secondary Carcinoma
  • Well-defined, smoothly marginated
  • Lung based
  • Multiple
    154
zoom view
Flow Chart 1.33.1: Cardiophrenic Angle Masses
 
Epicardial Fat Pad
  • Excessive deposition of fat in mediastinum
  • Obese patient
  • Cushing syndrome or excessive corticosteroid intake
  • Uncapsulated and extrapleural fat.
 
Lipoma
  • Uncommon
  • Well-defined, encapsulated, generally homogeneous
  • May contain thin fibrous septae
  • Inhomogeneous, poorly defined.
 
Lymph Nodes
  • Anterior diaphragmatic group of L.N. – 2 nodes, < 5 mm- is normal.
 
Causes of enlargement are:
  • U/L or B/L
    • Lymphoma
    • Lung, breast or colon cancer—metastasis.