94
CMDT 2013
6
Dermatologic Disorders Timothy G. Berger, MD
Dermatologic diseases are diagnosed by the types of lesions they cause. To make a diagnosis: (1) identify the type of lesion(s) the patient exhibits by morphology establishing a differential diagnosis (Table 6–1); and (2) obtain the elements of the history, physical examination, and appropriate laboratory tests to confirm the diagnosis. Unique clinical situations, such as the ill ICU patient, lead to different diagnostic considerations.
PRINCIPLES OF DERMATOLOGIC THERAPY ``Frequently Used Treatment Measures A. 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 (Soak and Smear). Bath oils can be used, but add little above the use of moisturizers, and may make the tub slippery, increasing the risk of falling.
B. Topical Therapy Nondermatologists should become familiar with a representative agent in each category for each indication (eg, topical corticosteroid, topical retinoid, etc). 1. Corticosteroids—Topical corticosteroid creams, lotions, ointments, gels, foams, and sprays are presented in Table 6–2. Topical corticosteroids are divided into classes based on 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. The potency of a topical corticosteroid may be dramatically increased by applying an occlusive dressing over the corticosteroid. Optimally, at least 4 hours of occlusion should be prescribed 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). 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 37–2). 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 mellitus, hypertension, osteoporosis, and other complications of systemic corticosteroids are very rare with topical corticosteroid therapy. 2. Emollients for dry skin (“moisturizers”)—Dry skin is not related to water intake but to abnormal function of the epidermis. Many types of emollients are available. Petrolatum, mineral oil, Aquaphor, Vanicream, and Eucerin cream are the heaviest and best. Emollients are most effective when applied to wet skin. If the skin is too greasy after application, pat dry with a damp towel. Vanicream is relatively allergen-free and can be used if allergic contact dermatitis to topical products is suspected. The scaly appearance of dry skin may be improved by urea, lactic acid, or glycolic acid-containing products provided no inflammation (erythema or pruritus) is present. 3. Drying agents for weepy dermatoses—If the skin is weepy from infection or inflammation, drying agents may be beneficial. The best drying agent is water, applied as repeated compresses for 15–30 minutes, alone or with aluminum salts (Burow solution, Domeboro tablets) or colloidal oatmeal (Aveeno). 4. Topical antipruritics—Lotions that contain 0.5% each of camphor and menthol (Sarna) or pramoxine hydrochloride 1% (with or without 0.5% menthol, eg, Prax, PrameGel, Aveeno Anti-Itch lotion) are effective antipruritic agents. Hydrocortisone, 1% or 2.5%, may be incorporated for its anti-inflammatory effect (Pramosone cream, lotion, or ointment). Doxepin cream 5% may reduce pruritus but may cause drowsiness. Pramoxine and doxepin are most effective when applied with topical corticosteroids. Monoamine oxidase inhibitors should be discontinued at least 2 weeks before treatment with doxepin. Topical capsaicin can be effective in some forms of neuropathic itch. Ice in a plastic bag covered by a thin cloth applied to itchy spots can be effective.