Seborrheic dermatitis
Also called seborrheic eczema, dandruff (mild scalp form)
An inflammatory response to Malassezia yeast in oily skin zones: scalp, eyebrows, nasolabial folds, ears, central chest. Common, chronic, and worse with stress; severe abrupt disease should prompt thinking about immunosuppression.
How it looks
Erythematous patches with greasy yellow scale involving the scalp margin, medial eyebrows, and nasolabial folds.
Rose is the lesion, grey the pattern the lesions make, green where on the body it lives.
Across skin tones
In deeply pigmented skin it commonly presents as hypopigmented patches or petaloid (flower-like) polycyclic lesions on the face, an appearance underrepresented in classic textbooks.
Symptoms & course
- Mild itch and flaking
- Waxes and wanes; worse in winter
Diagnostic approach
- Clinical diagnosis
- Consider HIV testing for sudden severe or refractory disease
Differential, and how to separate them
- Psoriasis
Favours it: Thicker plaques, silvery scale, extensor disease elsewhere
Against it: Sebopsoriasis overlaps, but greasy scale in seborrheic zones favours seb derm
- Rosacea
Favours it: Flushing, papulopustules on convexities
Against it: Seb derm scales in the folds; rosacea spares them and does not scale
Management principles
- Antifungal (ketoconazole) shampoo and cream as the backbone
- Short courses of mild topical corticosteroid for flares
Clinical pearl: Distribution is the diagnosis: grease zones plus fine yellow scale, in an otherwise well adult.
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