[Seborrheic dermatitis].

Seborrheic dermatitis is a frequent skin disorder in infancy and adulthood. It also often occurs in patients with HIV or neurologic disorders like Parkinson disease or mood disorders. It is characterized by greasy, yellow flakes or scales in areas of high sebaceous gland activity like the scalp, face, chest and upper back. Additionally, erythema and itching can be present. The etiology and pathogenesis of seborrheic dermatitis is unknown; however, the focus lies on the involvement of Malassezia yeasts or fatty acid metabolites of Malassezia, on hormones and immunologic factors. The diagnosis is usually a clinical one, based on history and the appearance and site of lesions. The therapy consists mainly of antifungal agents, corticosteroids, immunomodulators, and keratolytics. Because of the chronicity of the illness with frequent relapses, a treatment strategy in which effectiveness and potential side effects are weighed should be used.