Seborrheic Dermatitis

Noah S. Scheinfeld, MD, JD

Disclosures

A 40-year-old man presented with a 1-year history of a red scaly eruption in the scalp, behind the ears, and in the nasal alae. The eruption in the scalp was slightly pruritic. There was relative hypopigmentation in the skin of the eyebrows. Notably, annular, erythematous, scaly plaques manifested on the patient's chest (Figure). The patient had no other eruptions or medical problems. He took no medications. A KOH preparation of his chest was negative. A diagnosis of seborrheic dermatitis was made. He was prescribed desonide lotion 0.05% for his face and chest and selenium sulfide shampoo for his scalp. Six weeks later his eruption had almost totally resolved and he was told to continue the therapy as necessary.

Petaloid seborrheic dermatitis on the chest.

Seborrheic dermatitis manifests with erythematous plaques or patches often with white or yellow scale occurring in the scalp, the face (in particular the ears and nasal alae), the chest, anus, and the groin, the so-called "seborrheic areas." It often only effects the scalp, but it varies in extent (scant scaling in the scalp to exfoliative erythroderma) and morphology of lesions ( Table 1 ). Some think it can overlap with psoriasis in the scalp and term this sebopsoriasis. The annular variant manifested in this patient is not rare. In some persons, particularly in people of color, it sometimes appears simply as white, minimally scaly patches on the face, in particular around the eyebrows. It can become secondarily infected with gram-positive-cocci and with Candida.

The prevalence of seborrheic dermatitis is estimated at 1%–5% of the population, but I believe that simple scaling in the scalp is more common. It can occur in infants (in particular cradle cap). It is not common in children but appears in puberty and has a peak incidence in adults. It is less common in the elderly. It appears more commonly in men than in women.

The causes of seborrheic dermatitis are complex and include and the presence of sebaceous glands and sebum, overgrowth of Pityrosporum ovale (Malassezia furfur) , and activation and alteration function of complement. Some people believe that changes in humidity and season, trauma (e.g., scratching), and emotional stress also elicit or worsen seborrheic dermatitis. It also seems to have some relationship to immunological abnormalities and it is estimated that 90%–95% of patients with human immunodeficiency virus infection manifest with seborrheic dermatitis. It also seems increased in patients with neurological diseases such as Parkinson's disease (35% of patients). Other diseases associated with seborrheic dermatitis include epilepsy, congestive heart failure, obesity, chronic alcoholism, Leiner's disease, and zinc deficiency (which itself has a seborrheic dermatitis-like eruption). Severe or unresponsive eruptions diagnosed as seborrheic dermatitis should prompt a physician to test for HIV infection, zinc deficiency, and/or tinea.

Medications that can exacerbate or bring out seborrheic dermatitis include: auranofin, aurothioglucose, buspirone, chlorpromazine, cimetidine, ethionamide, gold, griseofulvin, haloperidol, interferon-α, lithium, methoxsalen, methyldopa, phenothiazines, psoralens, stanozolol, thiothixene, and trioxsalen.. A number of conditions can imitate the appearance of seborrheic dermatitis ( Table 2 ).

A variety of treatments are effective for the treatment of seborrheic dermatitis. The mainstays of treatment are mild topical steroids (class IV or weaker) and topical antifungal agents used once or twice a day, either used alone or in combination. Derma-Smoothe/FS (fluocinolone acetonide 0.01%; Hill Dermaceuticals, Inc., Sanford, FL) scalp oil is especially helpful when scalp plaques are thick. Corticosteroids in foam preparations have high patient acceptance among patients who have seborrheic dermatitis in their scalps. Other treatments include topical preparation of sulfur or sulfonamide combinations, propylene glycol, selenium sulfide 2.5% lotion, tea tree oil, lithium succinate, and benzoyl peroxide. Topical calcineurin inhibitors can be useful treatments, in particular, when rosacea and seborrheic dermatitis overlap. Severe cases can be treated with oral antifungal agents or phototherapy. Shampoos with antifungal agents, salicylic acid, tar, selenium sulfide, and zinc pyrithione all are useful to treat scalp seborrheic dermatitis and their effects may be increased when several shampoos are used alternatively (e.g., tar-Monday, zinc-Tuesday, selenium-Wednesday, etc.).

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