Seborrheic Dermatitis

Overview:

Seborrheic dermatitis is 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,^[1] immunologic abnormalities, and activation of complement. Its severity ranges from mild dandruff to exfoliative erythroderma.

Signs and Symptoms

History findings in seborrheic dermatitis may include the following:

·         Intermittent, active phases manifesting with burning, scaling, and itching, alternating with inactive periods; activity is increased in winter and early spring, with remissions commonly occurring in summer

·         In active phases, potential secondary infection in intertriginous areas and on the eyelids

·         Candidal overgrowth (common in infantile napkin dermatitis)

·         Generalized seborrheic erythroderma (rare)

Physical findings may include the following:

·         Scalp appearance ranging from mild, patchy scaling to widespread, thick, adherent crusts; plaques are rare; lesions may spread from the scalp onto the forehead, the posterior part of the neck, and the postauricular skin

·         Seborrheic skin lesions manifesting as scaling over red, inflamed skin; hypopigmentation (in blacks); oozing and crusting; blepharitis (occurring independently)

·         Lesion distribution following the oily and hair-bearing areas of the head and the neck; extension to submental skin can occur

·         Either of 2 distinct truncal patterns: (1) annular or geographic petaloid scaling or (2) pityriasiform variety (rare)

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T      The scalp appearance of seborrheic dermatitis varies from mild, patchy scaling to widespread, thick, adherent crusts. Plaques are rare. From the scalp, seborrheic dermatitis can spread onto the forehead, the posterior part of the neck, and the postauricular skin, as in psoriasis. Note the images below.

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·             Seborrheic dermatitis skin lesions manifest as branny or greasy scaling over red, inflamed skin. Hypopigmentation is seen in blacks. Infectious eczematoid dermatitis, with oozing and crusting, suggests secondary infection. A seborrheic blepharitis may occur independently.

·            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 the postauricular skin. An extension to submental skin can occur. Presternal or interscapular involvement is more common than nonscaling intertrigo of the umbilicus, axillae, inframammary and inguinal folds, perineum, or anogenital crease, which also may be present.

·             Two distinct truncal patterns of seborrheic dermatitis can occasionally occur. An annular or geographic petaloid scaling is the most common. A rare pityriasiform variety can be seen on the trunk and the neck, with peripheral scaling around ovoid patches, mimicking pityriasis rosea. Note the image below.

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Medical Care

Early treatment of flares is encouraged. Behavior modification techniques in reducing excoriations are especially helpful with scalp involvement.

Dandruff responds to more frequent shampooing or a longer period of lathering. Use of hair spray or hair pomades should be stopped. Shampoos containing salicylic acid, tar, selenium, sulfur, or zinc are effective and may be used in an alternating schedule

Ketoconazole topical

Available as ketoconazole cream 2% (Nizoral), ketoconazole foam (Extina), ketoconazole shampoo 2% (Nizoral 2%; prescription only in United States), ketoconazole shampoo 1%