Dandruff and Seborrheic Dermatitis: A Head Scratcher 390 generation of negative social image.5-7 Further, the field has been recently re-invigorated by the discovery of the fungal cause and the sequencing of the Malassezia genome. What is Dandruff? The relationship between dandruff and seborrheic dermatitis has at times been controversial. While most investigators regard seborrheic dermatitis of the scalp as severe dandruff, others believe that dandruff should be used to describe any flaking of the scalp.8-11 A normal scalp has few flakes and healthy looking, smooth skin (Figure 1). Dandruff is characterized by patches of loosely adherent flakes, usually accompanied by itching. Dandruff has the clinical feature of small white or gray flakes that accumulate diffusely on the scalp in localized patches. It does not exhibit apparent inflammation and is confined to the scalp. In seborrheic dermatitis, the flakes have progressed to being greasy with a yellow color. Seborrheic dermatitis flakes are frequent enough to appear as adherent mounds accompanied by inflammatory changes (seen as surface erythema). Seborrheic dermatitis varies in appearance, presenting as patches of red, flaking, greasy skin and differs from dandruff in that it can appear beyond the scalp, particularly the nasolabial folds, ears, eyebrows and chest. The key differentials in diagnosis of dandruff versus seborrheic dermatitis are visible redness or erythema and the Figure 1. Topical presentation of dandruff and seborrheic dermatitis