Seborrheic Dermatitis

Epidemiology:

• Common (1-3% of general population)

Common sites:

• (areas with high density of sebaceous glands)
• scalp
• forehead (esp. glabella)
• external auditory canal
• retroauricular area
• nasolabial folds
• presternal area

Gross features:

• macules and papules on an erythematous-yellow, often greasy base
• extensive scaling and crusting usually
• fissures, particularly retroauricular
• dandruff (scalp involvement)
• cradle cap in infants

Histologic features:

• spongiosis in early lesions
• acanthosis in chronic lesions
• mounds of parakeratosis at the ostia of hair follicles (follicular lipping)
• neutrophils and serum within
• superficial perivascular inflammatory infiltrate
• lymphocytes
• neutrophils
• HIV-infection:
• Apoptotic keratinocytes
• Plasma cells

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Malassezia furfur, a lipophilic yeast, may play a pivotal role
• also sebum production is involved
• HIV-infected individuals often develop a severe and difficult to treat form (83%)
• Parkinson’s patients have a higher incidence as well as increased sebum production
• Leiner disease
• Generalized seborrheic dermatitis in infants associated with diarrhea and failure to thrive

References:

• Robbins 2005