Seborrheic dermatitis

Seborrheic dermatitis is a common, inflammatory skin condition that causes flaky, white to yellowish scales to form on oily areas such as the scalp or inside the ear. It can occur with or without reddened skin.

CAUSES

Seborrheic dermatitis is thought to be due to a combination of an over production of skin oil and irritation from a yeast called malassezia.

Seborrheic dermatitis appears to run in families. Stress, fatigue, weather extremes, oily skin, infrequent shampoos or skin cleaning, use of lotions that contain alcohol, skin disorders (such as acne), or obesity may increase the risk.

Neurologic conditions, including Parkinson's disease, head injury, and stroke may be associated with seborrheic dermatitis.

SYMPTOMS

Seborrheic dermatitis can occur on many different body areas. Usually it forms where the skin is oily or greasy. Commonly affected areas include the scalp, eyebrows, eyelids, creases of the nose, lips, behind the ears, in the outer ear, and middle of the chest.

In general, symptoms of seborrheic dermatitis include:

• Skin lesions
• Plaques over large area
• Greasy, oily areas of skin
• Skin scales -- white and flaking, or yellowish, oily, and adherent -- "dandruff"
• Itching -- may become more itchy if infected
• Mild redness
• Hair loss

EXAMS AND TESTS

The diagnosis is based on the appearance and location of the skin lesions.

TREATMENT

You can treat flaking and dryness with over-the-counter dandruff or medicated shampoos. Shampoo the hair vigorously and frequently (preferably daily). Loosen scales with the fingers, scrub for at least 5 minutes, and rinse thoroughly. Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, ketoconazole, or selenium.

Shampoos or lotions containing selenium, ketoconazole, or corticosteroids may be prescribed for severe cases. To apply shampoos, part the hair into small sections, apply to a small area at a time, and massage into the skin. If on face or chest, apply medicated lotion twice per day. Recently, creams classified as topical immune modulators are being used.

Seborrheic dermatitis may improve in the summer, especially after outdoor activities.

OUTLOOK (PROGNOSIS)

Seborrheic dermatitis is a chronic (life-long) condition that can be controlled with treatment. It often has extended inactive periods followed by flare-ups. A more extreme form of this condition overlaps with psoriasis of the scalp and is called sebopsoriasis.