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Seborrheic
dermatitis (SD) is inflammation of skin with a high density of sebaceous
glands (face, scalp, upper trunk). The cause is unknown, but Pityrosporum ovale, a normal skin
organism, plays some role. SD occurs with increased frequency in
patients with HIV and in those with certain neurologic diseases.
Seborrheic dermatitis causes occasional pruritus, dandruff, and
yellow, greasy scaling along the hairline and on the face. Diagnosis
is clinical. Treatment is tar or other medicated shampoo and topical
corticosteroids and antifungals.
Despite the name, the composition and flow of sebum are usually normal. The incidence and severity of disease seem to be affected by genetic factors, emotional or physical stress, and climate (usually worse in cold weather). SD may precede or be associated with psoriasis (seborrhiasis). Patients with neurologic disease (especially Parkinson's disease) or HIV may have severe SD. Very rarely, the dermatitis becomes generalized.
The pathogenesis of SD is unclear, but its activity has been linked to the number of Pityrosporum yeasts present on the skin.
Symptoms,
Signs, and Diagnosis
Symptoms develop gradually, and the dermatitis is usually apparent only as dry or greasy diffuse scaling of the scalp (dandruff) with variable pruritus. In severe disease, yellow-red scaling papules appear along the hairline, behind the ears, in the external auditory canals, on the eyebrows, in the axillae, on the bridge of the nose, in the nasolabial folds, and over the sternum. Marginal blepharitis with dry yellow crusts and conjunctival irritation may develop. SD does not cause hair loss.
Newborns may develop SD with a thick, yellow, crusted scalp lesion (cradle cap); fissuring and yellow scaling behind the ears; red facial papules; and stubborn diaper rash. Older children may develop thick, tenacious, scaly plaques on the scalp that may measure 1 to 2 cm in diameter.
Diagnosis is clinical.
Treatment
In adults, zinc pyrithione, selenium sulfide, sulfur and salicylic acid , or tar shampoo should be used daily or every other day until dandruff is controlled and twice/wk thereafter. A corticosteroid lotion (eg, 0.01% fluocinolone acetonide solution, 0.025% triamcinolone acetonide lotion) can be rubbed into the scalp or other hairy areas bid until scaling and redness are controlled. For SD of the postauricular areas, nasolabial folds, eyelid margins, and bridge of the nose, 1% hydrocortisone cream is rubbed in bid or tid, decreasing to once/day when controlled; hydrocortisone cream is the safest corticosteroid for the face because fluorinated corticosteroids may produce adverse effects (eg, telangiectasia, atrophy, perioral dermatitis). In some patients, 2% ketoconazole cream or other topical imidazoles bid for 1 to 2 wk induce a remission that lasts for months. For eyelid margin seborrhea, a dilution of 1 part baby shampoo to 9 parts of water is applied with a cotton swab.
In infants, a baby shampoo is used daily, and 1% hydrocortisone cream is rubbed in bid. For thick lesions on the scalp of a young child, 2% salicylic acid in olive oil or a corticosteroid gel is applied at bedtime to affected areas and rubbed in with a toothbrush. The scalp is shampooed daily until the thick scale is gone.
Last full review/revision November 2005
Content last modified November 2005
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