Look At All the Skin and Mucous Membranes
A “peephole” diagnosis should be avoided; the whole organ should be examined. If the patient is not fully undressed, relevant lesions could be missed. However, it is useful to select one typical well-defined lesion to describe in detail, followed by an orderly and sequential system of examination so that no areas of the body are missed. The feet should always be examined in the presence of hand dermatitis so that a hypersensitivity reaction to a tinea infection or a concomitant hand tinea will not be missed. Erythema in dark-skinned people may be difficult to appreciate; it often is seen as postinflammatory hyperpigmentation.
Inspect for Distribution
Determine if the lesion is widespread or localized, unilateral or bilateral, symmetrical or asymmetrical. Symmetrical lesions commonly have internal causes (e.g., eczema, psoriasis); asymmetrical lesions have external causes (e.g., bacterial or fungal infections, allergic contact eczema). Is the lesion predominantly on the flexor (as in atopic dermatitis) or extensor (as in psoriasis) surfaces? A rash on the soles or palms occurs with erythema multiforme, secondary syphilis, and rickettsial infections. Determine if the distribution is confined either to protected areas or to light-exposed areas such as in collagen-vascular diseases, photosensitive reactions to drugs, and airborne contact dermatitis. Is the lesion predominantly centrifugal (affecting the extremities), as seen in erythema multiforme, Rocky Mountain spotted fever, and insect bites, or centripetal (sparing the extremities and concentrated on the trunk)? Intertriginous distribution (neck, axilla, groin) is found in candidiasis, some inflammatory fungal infections, and some forms of psoriasis.
Inspect the Mouth
Drug eruptions from sulfonamides, penicillin, streptomycin, quinine, and atropine often have associated mucosal erosions (enanthems) and crusts. Mucosal involvement is common in hand and foot lesions (e.g., hand-foot-andmouth disease), herpes, and syphilis. Oral lesions occur in lichen planus, autoimmune blistering diseases, and malignancies such as squamous cell carcinoma.
Inspect the Hair
In children, a triad of hair loss, scaling, and lymphadenopathy is diagnostic of tinea capitis. A high index of suspicion is warranted in inner city urban areas, where the condition is common. Evaluate for hair loss that is diffuse or localized and
compare areas such as the temporal and crown region to the occiput. Psoriasis and seborrheic dermatitis may present as scaling and desquamation. A hair pull test will reveal any increased hairs shed with a gentle pull.
Palpate the Skin
Palpate skin lesions to assess for tenderness, texture and consistency, firmness, fluctuance, and depth. Smooth skin has no irregularity. Uneven skin has fine scaling or some warty lesions. Rough skin feels like sandpaper and is characteristic of keratin/horn or crusts. Assessing the superficial skin for texture is done by palpation with the fingertips. Deeper palpation is done using the thumb and index fingers. Soft skin feels like the lips, normal skin like the cheeks, firm skin like the tip of the nose, and hard skin like the forehead. The depth of the lesion determines if it is on the surface or located within the dermis or subcutaneous tissue. An indurated base is a thickening in the depths of the lesion rather than on the surface.
Palpate the Regional Lymph Glands
Many viral exanthems will present with rash and lymphadenopathy. Palpation of the regional lymph glands may be of assistance in the diagnosis if neoplasm is suspected.
Perform an Abdominal Examination
The detection of hepatic or splenic enlargement may assist in the diagnosis of a systemic cause of skin disorders.