A 3-month-old African American boy is brought to the clinic with white spots on his face for one month (Figure 135-1). The child is otherwise in great health, eating well and gaining weight. The mother was negative for HIV during pregnancy. On physical exam, there are hypopigmented patches on the face especially at the hair line and under the eyebrows. There is visible scale in each of these patches. The hypopigmentation occurs secondary to the toxic effect of the Malassezia (Pityrosporum) on the melanocytes (as seen in tinea versicolor). The diagnosis of seborrheic dermatitis is made and treatment is begun with appropriate topical agents to treat the inflammation and the Malassezia. The mother is told to shampoo the infant’s hair with a selenium-based shampoo every 1 to 2 days and to apply 1 percent hydrocortisone cream to the hypopigmented areas twice daily for the next 2 weeks. At a 2-week follow-up, the scale is gone and the hypopigmentation is resolving.

A 13-year-old African American boy presented to clinic with a mildly pruritic central facial rash and scalp dandruff that had persisted for two years (Figure 135-2). There was no history to suggest an allergic contact dermatitis or drug allergy. On physical exam, confluent scaling and erythema with areas of hypopigmentation were noted in the naso-mesial folds and over the eyebrows. Additionally, diffuse scaling and erythema were noted throughout the scalp. The patient was diagnosed with seborrheic dermatitis. Patients with more pigmentation often show a raised lateral margin reminiscent of the advancing border of dermatophyte infections and subsequent postinflammatory hypopigmentation that can be temporarily disfiguring. This patient responded to ketoconazole 2 percent cream applied twice daily to the face and other non-hair-bearing areas and ketoconazole 2 percent shampoo twice weekly for his scalp. His hypopigmentation improved over time.

Seborrheic dermatitis is a common, chronic, relapsing dermatitis affecting sebum-rich areas of the body. Children and adults, males and females may be affected. Presentation may vary from mild erythema to greasy scales, and rarelyas erythroderma. Treatment is targeted to reduce inflammation and irritation, as well as to eliminate Malassezia fungus, whose exact role is not completely understood.

Seborrhea, seborrheic eczema, dandruff, and cradle cap (pityriasis capitis).

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  The prevalence of seborrheic dermatitis was 10 percent in children from infancy to 5 years of age in a skin survey of over 1,000 children in Australia. The highest rate was in the first 3 months of life, decreasing rapidly by the age of 1 year, after which it slowly decreased over the next 4 years. Most (72%) had disease classified as minimal to mild. Cradle cap occurred in 42 percent of the children examined, with 86 percent categorized as minimal to mild only.¹

  
  
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  Prevalence of scalp seborrheic dermatitis in a survey of male adolescents in Brazil was 11 percent. The prevalence was higher in persons with white skin and a higher body fat content.²

  
  
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  Seborrheic dermatitis affects 1 to 3 percent of the general population, 3 to 5 percent of young adults, and 20 to 83 percent of patients with AIDS.³

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  Seborrheic dermatitis is a chronic, superficial, localized inflammatory dermatitis that is found in sebum-producing areas of the body.

  
  
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  The actual cause of seborrheic dermatitis is not well understood. It appears to be related to the interplay between host susceptibility, environmental factors, and local immune response to antigens.^4–6

  
  
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  Patients with seborrheic dermatitis may be colonized with certain species of lipophilic yeast of the genus Malassezia; however, Malassezia is considered normal skin flora and unaffected persons also may be colonized.

  
  
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  Recent evidence suggests that Malassezia may produce different irritants or metabolites on affected skin.⁶

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  Infancy.

  
  
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  Male gender.

  
  
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  Immunocompromise (HIV/AIDS, Parkinson disease, or malignancy).

  
  
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  Stress.

  
  
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  Environmental factors (cold, dry weather).

The clinical diagnosis is made by history and physical examination. Figures 135-3 and 135-4 reveal erythema and scale across the eyebrows, forehead, central face, and scalp. Biopsy is not generally indicated unless ruling out other possibilities (see the following section “Differential Diagnosis”).

Clinical Features