APPROACH TO DERMATOLOGICAL DIAGNOSIS
- History taking: Onset and course
- Exacerbating or relieving factors.
- History of skin disease, atopy, autoimmune disease, diabetes mellitus or any immunosuppressive conditions.
- Occupational, social history.
- Psychological history.
- Allergy history.
- Drug history: Both topical and systemic drug including over-the- counter preparation.
- Closer inspection: Use magnifying lens or dermatoscope.
- Examination of skin, hair, nail and mucous membrane
- Type of lesion.
- Distribution pattern.
- Morphology pattern.
- General examination: Includes lymph node examination
- Skin findings for systemic disease.
CUTANEOUS SIGNS
Primary Lesions
Initial lesions those are not altered by natural evolution, infection, trauma or manipulations.
Papules: They are circumscribed, discrete, solid, epidermal elevation varying in size from a pinhead to 1 cm (0.5 mm–1 cm) (Figs. 5 to 8).
Plaques: They are circumscribed, elevated solid lesion due to increased thickness of epidermis and/or cells or deposits within the dermis >1 cm in diameter. May be distinct lesion or formed by a confluence of papules (Figs. 9 and 10).
Nodules: Dome shaped, elevated, circumscribed lesions involving dermis and may extent to the subcutis; diameter greater than 1 cm and on palpation can be compressible, soft, rubbery or firm (Figs. 11 to 14).
Pusule: Elevated, circumscribed pus (infectious-neutrophil or sterial) containing lesion <1 cm diameter (Figs. 19 and 20).
Wheals: Evanescent, edematous, pruritic elevated lesion of various sizes (Fig. 21).
Secondary Lesions
Lesions those are altered by natural evolution, infection, trauma or manipulations.
Crust: Dried serum, pus, blood mixed with epithelial and sometimes bacterial debris. When crusts become detached, the base may be dry or red and moist (Figs. 22 and 23).
Erosion: Partial or full loss of epidermis. Heals without a scar (Fig. 26).
Excoriation: Linear or punctuate abrasion by trauma (Fig. 27).
Fissures: Vertical loss of epidermis and partial or full thickness of dermis (Fig. 28).
Ulcers: Rounded or irregularly shaped complete loss of epidermis plus partial or complete loss of dermis (Fig. 29).
Hypertrophy: Deposition of excessive amounts of collagen which are confined in wound area (Fig. 31A and B).
Keloid: Deposition of excessive amounts of collagen which are not confined in wound area and are extended in normal surrounding area in claw like fashion (Fig. 32).
Petechiae, Purpura, and Ecchymosis
Petechiae
Pinpoint spots that appear on the skin due to extravasation of RBC.
- ≤3 mm diameter.
Purpura
Nonpalpable purpura are extravasation of blood in skin and mucous membrane <1 cm in diameter (Figs. 35 and 36).
Causes are:
- Defective coagulation: anticoagulant use, hepatic insufficiency and vitamin k deficiency.
- Poor dermal support of blood vessels.
- Platelet dysfunction.