Seborrheic Dermatitis

Signs and symptoms of seborrheic dermatitis include red areas of inflamed skin with greasy-looking, yellowish scales that affect areas with a high density of sebaceous glands, such as the scalp, face, behind the ears, and upper chest. 

In infants, seborrheic dermatitis tends to affect the scalp, and it is commonly referred to as “cradle cap.” However, it can also cause redness and scaling in the face, ears, neck, diaper area, and skin folds. Unlike in adults, seborrheic dermatitis does not usually cause itching in infants. In some cases, a thick layer of yellowish, greasy-looking scale can cover the entire scalp. Over time, the scale becomes flaky and typically brushes off with the condition self-resolving in a few months. 

In adults, seborrheic dermatitis is a chronic, relapsing condition that typically affects the scalp, face, and upper trunk. Dandruff is considered to be a mild form of seborrhoeic dermatitis where inflammation is not present. It is characterized by light flaking on the scalp that may spread to the hairline, retroauricular area, and eyebrows. More severe forms of scalp seborrheic dermatitis present with visible inflammation, consisting of patchy, orange to salmon-colored plaques covered with greasy scaling. Lesions may extend to the retroauricular area, where they often develop fissures, oozing, and crusting and to the outer canal of the ear, sometimes with intense itchiness and secondary bacterial infection.

On the face, seborrheic dermatitis tends to affect the eyebrows, eyelids, and nasolabial folds, though lesions may extend to the cheeks and malar areas in a butterfly distribution. In some cases, there may be redness of the free margin of the eyelids and yellow crusting within the eyelashes, leading to blepharitis (i.e., inflammation of the eyelids).

Seborrheic dermatitis in the trunk is less common, and it often affects moist, skin-to-skin contact regions, such as the armpits, under the breasts, and the groin. In individuals with HIV, seborrheic dermatitis tends to be more extensive and severe, and it sometimes involves unusual sites, such as the extremities.

Treatment of seborrheic dermatitis varies according to the severity of the condition. In infants, cradle cap can be treated with frequent shampooing with non-medicated baby shampoo or emollients, like petroleum jelly or baby oil, to help loosen the scales. The softened scales can then be removed with a cloth or soft toothbrush. More extensive or persistent cases may require short-term treatment with a topical antifungal cream or low-potency topical corticosteroid. 

Adult individuals with mild disease that presents as minimal scalp scaling are generally treated with over-the-counter dandruff shampoos containing selenium sulfide, zinc pyrithione, or coal tar as well as antifungal agents, like shampoos or creams, until remission is achieved.