Shiitake dermatitis: a report of 3 cases and review of the literature.

Shiitake mushroom-induced toxicoderma, or shiitake dermatitis, is a widely recognized phenomenon in Japan, China, and Korea but only recently has been reported outside of Asia. Affected individuals develop a characteristic pattern of whiplike, linear, erythematous wheals within 1 to 2 days after consumption of raw or cooked shiitake mushrooms. Lentinan, a polysaccharide component of shiitake mushrooms with antitumor properties, is thought to instigate a toxic reaction, resulting in the appearance of a rash. Shiitake dermatitis is self-limited and typically resolves within days to weeks of its appearance.