Pellagra dermatitis

Dermatitis due to niacin deficiency (pellagra). The term "pellagra" derives from the Italian words for "rough skin." The condition is characterized by an erythematous, blistering rash that may be pruritic or painful. The rash occurs in areas of sun exposure and is therefore often seen around the neck ("Casal's necklace"), arms, hands, or malar area.