As dermatologic evaluation relies heavily on the objective cutaneous appearance, physical examination is often performed prior to taking a complete history in pts presenting with a skin problem. A differential diagnosis can usually be generated on the basis of a thorough examination with precise descriptions of the skin lesion(s) and narrowed with pertinent facts from the history. Laboratory or diagnostic procedures are then used, when appropriate, to clarify the diagnosis.
Examination of skin should take place in a well-illuminated room with pt completely disrobed. Helpful ancillary equipment includes a hand lens and a pocket flashlight to provide peripheral illumination of lesions. An ideal examination includes evaluation of the skin, hair, nails, and mucous membranes. The examination often begins with an assessment of the entire skin viewed at a distance, which is then narrowed down to focus on the individual lesions.
As illustrated in Fig. 60-1, the distribution of skin lesions can provide valuable clues to the identification of the disorder: generalized (systemic diseases); sun-exposed (SLE, photoallergic, phototoxic, polymorphous light eruption, porphyria cutanea tarda); dermatomal (herpes zoster); extensor surfaces (elbows and knees in psoriasis); flexural surfaces (antecubital and popliteal fossae in atopic dermatitis).
The distribution of some common dermatologic diseases and lesions.
Can describe individual or multiple lesions: Linear (contact dermatitis such as poison ivy); annular—“ring-shaped” lesion (erythema chronicum migrans, erythema annulare centrificum, tinea corporis); iris or target lesion—two or three concentric circles of differing hue (erythema multiforme); nummular—“coin-shaped” (nummular eczema); morbilliform—“measles-like” with small confluent papules coalescing into unusual shapes (measles, drug eruption); herpetiform—grouped vesicles, papules, or erosions (herpes simplex).
Cutaneous changes caused directly by disease process (Table 60-1).
TABLE 60-1Description of Primary Skin Lesions ||Download (.pdf) TABLE 60-1 Description of Primary Skin Lesions
|Macule: A flat, colored lesion, <2 cm in diameter, not raised above the surface of the surrounding skin. A “freckle,” or ephelid, is a prototype pigmented macule. |
|Patch: A large (>2 cm) flat lesion with a color different from the surrounding skin. This differs from a macule only in size. |
|Papule: A small, solid lesion, <0.5 cm in diameter, raised above the surface of the surrounding skin and hence palpable (e.g., a closed comedone, or whitehead, in acne). |
|Nodule: A larger (0.5–5.0 cm), firm lesion raised above the surface of the surrounding skin. This differs from a papule only in size (e.g., a dermal nevomelanocytic nevus). |
|Tumor: A solid, raised growth >5 cm in diameter. |
|Plaque: A large (>1 cm), flat-topped, raised lesion; edges may either be distinct (e.g., in psoriasis) or gradually blend ...|