1. Seborrheic dermatitis Dr. Majdy Naim

2. Seborrheic dermatitis a papulosquamous disorder patterned on the sebum-rich areas of the scalp, face, and trunk In addition to sebum, this dermatitis is linked to Malassezia, immunologic abnormalities, and activation of complement

3. Commonly aggravated by changes in humidity, changes in seasons, trauma (eg, scratching), or emotional stress. The severity varies from mild dandruff to exfoliative erythroderma.

4. Pathophysiology normal levels of Malassezia but an abnormal immune response

5. Age The usual onset occurs with puberty. It peaks at age 40 years and is less severe, but present, among older people. In infants, it occurs as cradle cap or, uncommonly, as a flexural eruption or erythroderma.

6. Frequency :3-5 %, dandruff 15-20% Race: Seborrheic dermatitis occurs in persons of all races. Sex: The condition is slightly worse in males than in females.

7. Scalp appearance varies from mild, patchy scaling to widespread, thick, adherent crusts Skin lesions manifest as greasy scaling over red, inflamed skin Distribution follows the oily and hair- bearing areas of the head and the neck, such as the scalp, the forehead, the eyebrows, the lash line, the nasolabial folds, the beard, and postauricular skin.

15. Treatment Topical corticosteroids Dandruff responds to more frequent shampooing Selenium sulfide (2.5%), ketoconazole, and ciclopirox shampoos may help by reducing Malassezia yeast scalp reservoirs