Although many skin disorders are easily recognized by simple inspection, the history and physical examination are often necessary for accurate assessment. The entire body surface, mucous membranes, conjunctiva, hair, and nails should always be examined thoroughly under adequate illumination. The color, turgor, texture, temperature, and moisture of the skin and the growth, texture, caliber, and luster of the hair and nails should be noted. Skin lesions should be palpated, inspected, and classified on the bases of morphology, size, color, texture, firmness, configuration, location, and distribution. One must also decide whether the changes are those of the primary lesion itself or whether the clinical pattern has been altered by a secondary factor such as infection, trauma, or therapy.
Primary lesions are classified as macules, papules, patches, plaques, nodules, tumors, vesicles, bullae, pustules, wheals, and cysts.
A macule represents an alteration in skin color but cannot be felt.
When the lesion is >1 cm, the term patch is used.
Papules are palpable solid lesions <0.5–1 cm, whereas nodules are larger in diameter.
Tumors are usually larger than nodules and vary considerably in mobility and consistency. Vesicles are raised, fluid-filled lesions <0.5 cm in diameter; when larger, they are called bullae. Pustules contain purulent material.
Wheals are flat-topped, palpable lesions of variable size, duration, and configuration that represent dermal collections of edema fluid.
Cysts are circumscribed, thick-walled lesions that are located deep in the skin; they are covered by a normal epidermis and contain fluid or semisolid material.
Aggregations of papules are referred to as plaques.
Primary lesions may change into secondary lesions, or secondary lesions may develop over time where no primary lesion existed. Primary lesions are usually more helpful for diagnostic purposes than secondary lesions. Secondary lesions include scales, ulcers, erosions, excoriations, fissures, crusts, and scars.
Scales consist of compressed layers of stratum corneum cells that are retained on the skin surface.
Erosions involve focal loss of the epidermis, and they heal without scarring.
Ulcers extend into the dermis and tend to heal with scarring. Ulcerated lesions inflicted by scratching are often linear or angular in configuration and are called excoriations.
Fissures are caused by splitting or cracking; they usually occur in diseased skin.
Crusts consist of matted, retained accumulations of blood, serum, pus, and epithelial debris on the surface of a weeping lesion.
Scars are end-stage lesions that can be thin, depressed and atrophic, raised and hypertrophic, or flat and pliable; they are composed of fibrous connective tissue.
Lichenification is a thickening of skin with accentuation of normal skin lines that is caused by chronic irritation (rubbing, scratching) or inflammation.
If the diagnosis is not clear after a thorough examination, one or more diagnostic procedures may be indicated