Diagnosis of Skin Disorders

Morphology

Diagnosis of Skin Disorders

Every skin disease produces a characteristic primary skin lesion. This chapter will group diseases according to the types of lesions they cause and guide the reader through the history, physical findings, and laboratory tests that discriminate among the differential diagnoses.

History

A detailed history is important, though in the case of skin cancer or moles (nevi) the physical examination takes precedence. Important components of a history include systemic disorders; prescription, over-the-counter, and alternative systemic and topical medications; and exposure to physical and chemical agents in the home and work environments.

Physical Examination

It is best to examine the entire skin surface, including the nails, scalp, palms, soles, and mucous membranes, in bright light. Total skin examination allows recognition of typical disease patterns and ensures that no potentially important lesions are overlooked. In examining the head for skin cancer, special attention should be paid to the lid margins, nose, ears, and lips—areas of sun exposure.

Principles of Dermatologic Therapy

Frequently Used Treatment Measures

Bathing

Soap should be used only in the axillae and groin and on the feet by persons with dry or inflamed skin. Soaking in water for 10–15 minutes before applying topical corticosteroids enhances their efficacy.

Topical Therapy

In general, topical agents used by prescription are supplied in only one strength. Exceptions include hydrocortisone (1% and 2.5%); triamcinolone acetonide cream and ointment (0.025% and 0.1%) or solution (0.1%); and fluocinolone cream, ointment, or solution (0.01%), or cream and ointment (0.025%). There is little evidence that one concentration has clinical effects that are significantly different from another. Nondermatologists should become familiar with a few agents and use them properly rather than try to master the universe of topical agents.

Corticosteroids

Representative topical corticosteroid creams, lotions, ointments, gels, and sprays are presented in Table 6–1. Specific indications for topical corticosteroid therapy will be discussed in the context of specific dermatologic entities. Topical corticosteroids are divided into classes based on their potency. There is little (except price) to recommend one agent over another within the same class. For a given agent, an ointment is more potent than a cream; however, ointments are generally more greasy. The potency of a topical corticosteroid may be dramatically increased by applying an occlusive dressing over the corticosteroid. At least 4 hours of occlusion is required to enhance penetration. Such dressings may include gloves, plastic wrap, or plastic occlusive suits for patients with generalized erythroderma or atopy. Caution should be used in applying topical corticosteroids to areas of thin skin (face, scrotum, vulva, skin folds, ear canal). Topical corticosteroid use on the eyelids may result in glaucoma or cataracts. One may estimate the amount of topical corticosteroid needed by using the "rule of nines" (as in burn evaluation; see Figure 38–2). In general, it takes an average of 20–30 g to cover the body surface of an adult once. Systemic absorption does occur, but adrenal suppression, diabetes, hypertension, osteoporosis, and other complications of systemic corticosteroids are very rare with topical corticosteroid therapy (see photograph); (see photograph).