dermatologic disorders
Seborrheic Dermatitis
Introduction
Seborrheic dermatitis is a common inflammatory condition of skin regions with a high density of sebaceous glands (eg, face, scalp, sternum). The cause is unknown, but species ofMalassezia, a normal skin yeast, play an important role. This dermatitis occurs with increased frequency in patients with HIV and in those with certain neurologic disorders. Seborrheic dermatitis causes occasional pruritus, dandruff, and yellow, greasy scaling on the scalp, along the hairline, and on the face. Diagnosis is made by examination. Treatment is with antifungals, topical corticosteroids, tar, and keratolytics. (See also Definition of Dermatitis .) Despite the name, the composition and flow of sebum are usually normal. The pathogenesis of seborrheic dermatitis is unclear, but its activity has been linked to the number ofMalasseziayeasts present on the skin and to the inflammatory reaction to them. Seborrheic dermatitis occurs most often in infants, usually within the first 3 months of life, and in adults aged 30 to 70 years. The incidence and severity of disease seem to be affected by genetic factors, emotional or physical stress, and climate (usually worse in cold weather). Seborrheic dermatitis may precede or be associated with Psoriasis (called seborrhiasis or sebopsoriasis). Seborrheic dermatitis may be more common and more severe among patients with neurologic disorders (especially 