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Seborrheic
dermatitis (SD) is inflammation of skin that has a high density
of sebaceous glands (eg, 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.
SD causes occasional pruritus, dandruff, and yellow, greasy scaling
along the hairline and on the face. Diagnosis is made by examination.
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 pathogenesis of seborrheic dermatitis (SD) is unclear, but its activity has been linked to the number of Pityrosporum yeasts present on the skin. 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 (called seborrhiasis). SD may be more common and more severe among patients with neurologic diseases (especially Parkinson's disease) or HIV/AIDS. Very rarely, the dermatitis becomes generalized.
Symptoms and Signs
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
Diagnosis is made by physical examination. SD may occasionally be difficult to distinguish from other disorders, including psoriasis, atopic dermatitis or contact dermatitis, tinea, and rosacea.
Treatment
Adults:
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 twice daily 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 2 or 3 times daily, decreasing to once/day when controlled; hydrocortisone cream is the safest corticosteroid for the face because fluorinated corticosteroids may cause adverse effects (eg, telangiectasia, atrophy, perioral dermatitis). In some patients, 2% ketoconazole cream or other topical imidazoles applied twice daily 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 water is applied with a cotton swab.
Infants and
children:
In infants, a baby shampoo is used daily, and 1% hydrocortisone cream is rubbed in twice daily. 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 September 2009 by Karen McKoy, MD, MPH
Content last modified September 2009
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