A case of flagellation

Abstract

Conflict of interest: none declared A 58‐year‐old man presented with a 3‐day history of a striking flagellate dermatitis on his thighs and trunk (Fig. 1a,b), which were intensely pruritic. There was no dermographism. He had taken no new medication but had been on antiretroviral therapy for human immunodeficiency virus for many years. There were no other symptoms. Full blood count, including eosinophil count, and measurement of serum creatine kinase were normal. The previous night he had eaten a Chinese meal. ... A skin biopsy was performed (Fig. 2). He was treated with antihistamines and potent topical corticosteroids. The dermatitis settled within 2 weeks, leaving no pigmentary change. ... Histological sections showed mild to moderate spongiosis with focal hyperkeratosis, mid‐parakeratosis and minimal exocytosis of lymphocytes. In the superficial and mid dermis there was a mild, perivascular, lymphohistiocytic inflammatory cell infiltrate. What is your diagnosis? Flagellate dermatitis due to shiitake mushroom ingestion.