Uterine fibroids (leiomyomata) are benign tumors of the uterus primarily composed of smooth muscle and fibrous connective tissue. They range in size from seedlings to large uterine tumors. They may or may not be symptomatic.
The different terms are fibromyoma, myofibroma, myoma, fibroma, leiomyofibroma, fibroleiomyoma, and fibroid.
- Fibroid is the least accurate term to be used. Leiomyoma is a reasonably accurate term. It emphasizes the origin from smooth muscle cells and predominance of smooth muscle component.
- Leiomyomas are the most common tumors of female pelvis (Fig. 1.1) thus the most common indication for hysterectomy.
The true incidence and prevalence of uterine fibroids in the general female population are unknown because the condition is frequently asymptomatic and therefore not identified.
Incidence increases with age during the reproductive years such that cases occur in 20–50% of women older than 30 years.
These are benign tumors mainly composed of smooth muscles along with varying amount of fibrous connective tissue. They are well circumscribed but not capsulated.
- Racial predominance: More common in black women than in white. There is no explanation for this racial difference. Leiomyomata also are larger and occur at a younger age in black women.
- Genetic predisposition: Patients with leiomyomata often have a positive family history of leiomyoma.
- There is possibility of gene coding in development of leiomyomata.
- The true genetic contribution to the development of leiomyomas still needs to be defined.
- Estrogen dependence: Continuous estrogen secretion is the most important underlying risk factor in the development of leiomyoma.
- The evidence in support of estrogen and progesterone is impressive.
- Myomas are rarely found before puberty.
- The growth of leiomyoma usually ceases after menopause. Actual regression in the tumor size may occur.
- New myomas rarely appear after menopause. Possibility of malignant change should be ruled out in a leiomyoma, which enlarges after menopause.
- Association of leiomyomas with endometrial hyperplasia, abnormal uterine bleeding, and endometrial hyperplasia.
- Myomas increase in size during pregnancy and with combined contraceptive pills. Myomas tend to shrink after delivery. Mifepristone, a progesterone receptor inhibitor and gonadotropin-releasing hormone (GnRH) agonist cause reduction in the size of leiomyomas.
- Less common in smokers because of associated hypoestrogenic state.
- Parity: Higher risk in older nulliparous women. Relative risk decreases with each pregnancy.
- Obesity: Conversion of androgens to estrogens by fat aromatase increases the risk in obese women.
- Effect of pregnancy: Significant enlargement of leiomyoma during pregnancy proves relation of estrogen and progesterone to the growth of leiomyoma. The fibroids are often associated with adenomyosis, pelvic endometriosis, and pelvic inflammatory disease.
- A pseudocapsule is seen on ultrasonography (USG) scan, which differentiates it from normal myometrium.
- A typical myoma is well-circumscribed tumor with a pseudocapsule.
- It is firm in consistency. The cut surface is pinkish white and has a whorled appearance. The capsule consists of connective tissue, which fixes the tumor to the myometrium (Fig. 1.2).
- The blood vessels lie in the capsule and send radial branches into the myoma (Fig. 1.2).
- Degeneration is noticeable early and most frequently in the central part of the tumor due to least blood supply (Figs. 1.3A and B).
- Intramural (interstitial) 75%
- Submucous 15%
- Subserous 10%.
They may also arise from:
- Round ligament
- Utero-ovarian ligament
- Uterosacral ligaments
- Cervical, submucous, and broad ligament fibroids are usually single (Flowchart 1.1).
Secondary Changes in Fibroid
- Atrophic changes occur due to diminished vascularity after menopause.
- After childbirth, the tumor also gets much smaller in size.
- GnRH agonists can cause up to 50% reduction in size, which regrows after stopping the therapy.
Phosphates and carbonates are deposited in the periphery along the course of vessels.
In old patients with long-standing myomas, they are like womb stones in graveyard.
- Most often seen in pregnant patients with leiomyomas.
- It is not uncommon to see it in painful myomas in women over the age of 40.
- The lady may present with severe abdominal pain.
- It is the most common type of degeneration affecting fibroids of all sizes except the tiny ones.
- It is common in myomas having more connective tissues.
- The least vascular central part of the tumor is the most common site.
- The consistency changes to soft elastic as compared to firm consistency of fibroid.
- Cut surface shows areas of irregular homogeneous tissue with loss of whorl pattern.
- On microscopic examination, both the muscle and fibrous tissue show hyaline changes.
- Incidence is less than 0.5% of all myomas.
- Intramural and submucous tumors have a higher potential for sarcomatous change than subserous change. It is rare for the malignant change to develop in women under 40 years.
- If a tumor grows rapidly in a postmenopausal woman along with bleeding per vaginam (PV).
- The consistency is soft and friable and not firm like a simple myoma.
- Nonencapsulation of the tumor is an important sign. Sarcoma is highly malignant and spreads by bloodstream.
DIFFERENTIAL DIAGNOSIS OF MYOMAS
Sometimes fibroids can be confused with other lesions in pelvis. A detailed differential diagnosis has been tabulated in Table 1.1.
COMPLICATIONS OF MYOMAS
- Torsion: A pedunculated subserous myoma may undergo rotation at the site of its attachment to the uterus. Rarely, patient may present with acute abdominal pain due to torsion.
- Wandering or parasitic myoma: Rarely, a rotated pedunculated myoma may adhere to the adjacent viscera, obtain a fresh blood supply from it, and be detached completely from the uterus.
Table 1.1 Differential diagnosis in fibroids.DiseaseDifferentiating signs/symptomsDiagnostic testsAdenomyosis (Fig. 1.6)Congestive dysmenorrhea
Endometrial polyp (Fig. 1.7)Spasmodic dysmenorrheaIntermenstrual spotting
- Distinguished by histopathological examination
- Imaging with pelvic ultrasonography and MRI
Endometrial hyperplasia (Fig. 1.8)Heavy and irregular bleeding PV with passage of clots
- Sonohysterography (SHG) shows a well-circumscribed isoechoic polypoid mass with stalk contained within the endometrial stripe
- T2-weighted MRI images may show decreased signal intensity compared with endometrium
Endometrial carcinoma (Fig. 1.9)Because of the high prevalence of uterine fibroids in the general female population, a substantial number of patients with endometrial carcinoma will present with abnormal vaginal bleeding or discharge in association with uterine fibroids
- Hysteroscopic-guided endometrial biopsy and curettage followed by histopathology
Uterine sarcoma (leiomyosarcoma, endometrial stromal sarcoma, and mixed mesodermal tumor) (Fig. 1.10)Rapid growth of the tumor may be present in uterine sarcomas
- Endometrial sampling: An abnormal endometrial biopsy would show either precursor histology for endometrial carcinoma (simple/complex hyperplasia or simple atypical/complex atypical hyperplasia) or frank endometrial carcinoma
- Dilatation and curettage: Persistence of irregular vaginal bleeding despite a negative endometrial biopsy should be pursued by dilatation and curettage
Pregnancy (Fig. 1.11)Symptoms of pregnancy (e.g. morning sickness) and missed menstrual period are associated with abdominal expansion over a few weeks
- No test can reliably diagnose uterine sarcoma
- Serial MRI can identify rapid uterine growth and show characteristics associated with sarcomas such as indistinct borders and invasion into contiguous organs
Ovarian cancer (Figs. 1.12A to C)Ovarian cancer is differentiated by rapid tumor growth associated with atypical age for leiomyoma (e.g. postmeno-pausal women not on hormone replacement therapy), rapid weight loss, or ascites
- Pelvic ultrasonography visualizes the pregnancy sac
- The urine or blood beta-hCG pregnancy test is positive
Tumors of the GI tract and urinary system, lymphomas, and bone tumors (Figs. 1.13A to C)These serious conditions are differentiated by rapid tumor growth associated with atypical age for leiomyoma (e.g. postmenopausal women not on hormone replacement therapy), surrounding tissue invasion, rapid weight loss, or ascites.
- Pelvic ultrasonography and MRI are useful first-line investigations. MRI may show characteristic low-signal intensity on T2-weighted images seen with uterine fibroids, may show surrounding tissue invasion, and can more exactly define the origin of pelvic masses
- Pelvic ultrasonography and MRI are useful first-line investigations
- Surgery and histopathological examination
(GI: Gastrointestinal: hCG: Human chorionic gonadotropin; MRI: Magnetic resonance imaging: PV: Per vaginam)
- Inversion of uterus can occur due to fundal submucous myoma.
- Capsular hemorrhage: If one of the large veins overlying a subserous myoma ruptures and profuse intraperitoneal hemorrhage may occur leading to hemorrhagic shock.
- Infection: Blood stained foul-smelling discharge may occur in submucous myoma and myomatous polyp. Infection is common in puerperium and can cause puerperal sepsis too. Infected myomatous polyp can cause delayed postpartum hemorrhage (PPH) or sepsis.
- Associated endometrial carcinoma: In women over 40 years of age, associated endometrial carcinoma can occur in 3% cases. Associated hyperestrogenism is the predisposing factor in both the cases.
- Intermenstrual bleeding
- Continuous bleeding PV
- Postmenopausal disorders.
- Abdominal pain
- Spasmodic dysmenorrhea
- Lump in abdomen
- Mass protruding into the vagina
- Pressure symptoms on adjacent viscera—bladder, ureters, and rectum
- Miscarriage, early labor, and PPH
- Uterine inversion
- Excessive discharge PV
- About 50% of fibroids are asymptomatic detected on routine check-up and USG.
ACUTE CLINICAL CONDITIONS
Acute clinical conditions associated with leiomyomata are:
- Acute retention of urine
- Acute abdominal pain due to red degeneration in fibroid due to associated pregnancy
- Torsion of a pedunculated polyp
- Sarcomatous change
- Rare entity of thromboembolism in labor.
- Pallor—due to low hemoglobin caused by heavy periods.
- Abdominal lump—a mass arising out of pelvis with smooth margins, firm in consistency, with well-defined margins, smooth or bossy surface.
- The mass is mobile from side to side unless it is too big in size.
- The uterus feels enlarged with regular or bossy margins depending upon the number and size of myomas.
- Cervical fibroid—normal uterus is perched on top of the tumor.
- Broad-ligament fibroid displaces the uterus to the opposite side.
- In a myomatous polyp—cervical os is open and its lower pole is felt.
- In submucous fibroids, the uterus is uniformly enlarged.
- Fibroid is the most common pelvic tumor.
- Incidence of symptomatic fibroids varies between 3% and 10%.
- Myomas are more common in nulliparous women.
- Prevalence is highest between 35 years and 45 years of age.
- Fibroids may remain asymptotic (75%). However, depending upon their size, number, and location, they may cause menstrual irregularities, pain, pressure symptoms, infertility, and complications during pregnancy.
- Hyaline degeneration is the most common secondary change.
- Sarcomatous change is extremely rare (<0.5%).
- Red degeneration occurs mainly in pregnancy and puerperium.
Fibroid tumors are very common and affect all age groups. They can grow at various sites and can clinically present in multiple ways. A clear diagnosis is required and ultrasound is the best modality for that. A lot of things can confuse a clinician like adenomyosis, polyps and solid ovarian tumors.
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