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Seborrheic dermatitis is a common, chronic papulosquamous disorder affecting infants and adults alike. It is characteristically found in regions of the body with high concentrations of sebaceous follicles and active sebaceous glands including the face, scalp, ears, upper trunk, and flexures (inguinal, inframammary, and axillary).1 Less commonly involved sites include interscapular, umbilical, perineum, and the anogenital crease.2 The dermatitis presents with pink to erythematous, superficial patches and plaques with a yellow, branny and sometimes greasy scale. Excessive flaking on the face and scalp can lead to social embarrassment which can have a negative impact on one's quality of life, especially in women, younger patients, and those with a higher educational level.3 Mild forms are most commonly encountered, but severe psoriatic and erythrodermic forms can be seen as well.1 Seborrheic dermatitis is one of the most common dermatoses seen in human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) patients along with certain neurological disorders such as Parkinson disease.4,5 These patients tend to have widespread, erythrodermic, and treatment resistant forms. Severe forms are also seen with immunosupression in premature infants and congestive heart failure patients.6,7 African-Americans and other darkly pigmented races are susceptible to the annular or petaloid variant of seborrheic dermatitis, which may be confused for discoid lupus, secondary syphilis, or sarcoidosis.8 A rare pityriasiform variety of seborrheic dermatitis with ovoid scaling patches can be seen on the trunk and the neck, mimicking pityriasis rosea and secondary syphilis. A higher incidence of seborrheic dermatitis is also seen in patients with alcoholism and endocrinologic diseases that lead to obesity.9
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Seborrheic dermatitis is separated into two age groups, an infantile self-limited form primarily during the first 3 months of life and an adult form that is chronic. A male predominance is seen in all ages, without any racial predilection, or horizontal transmission. The prevalence of seborrheic dermatitis is 3%–5% of young adults, and 1%–5% of the general population, although its lifetime incidence is significantly higher.10
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In 1887, Unna first described seborrheic dermatitis. In 1894, Unna and Sabouraud hypothesized that yeast (Malessezia), bacteria, or both were responsible for causing seborrheic dermatitis, as both were cultured in high quantities from these patients.11 In 1984, Shuster showed that seborrheic dermatitis could be managed with oral ketoconazole, which has been further ...