Abstract
Shiitake mushroom dermatitis is a well-documented phenomenon in the literature seen after consuming raw or undercooked shiitake mushrooms (Lentinus edodes). However, systemic features resembling a drug reaction with eosinophilia and systemic symptoms (DRESS) are rare. We report a case of severe shiitake mushroom dermatitis with atypical systemic features resembling DRESS. A 51-year-old man presented with acute unilateral periorbital oedema and flagellate erythema with no obvious drug precipitants and was initially managed as allergic contact dermatitis in the emergency department. Further inquiry revealed a history of raw shiitake mushroom ingestion 48 h before the onset of symptoms, which led to a working diagnosis of shiitake mushroom dermatitis. Skin biopsies showed mixed spongiotic and interface inflammatory reactions with a perivascular lymphocytic infiltrate and marked eosinophilia supportive of shiitake mushroom dermatitis. Rheumatological causes of flagellate erythema and periorbital oedema were excluded from clinical and laboratory findings. The patient initially presented with apyrexia and mild eosinophilia but then developed pyrexia, hypereosinophilia, neutrophilia and transaminitis. He subsequently developed bilateral periorbital oedema with his flagellate erythema, both of which were resolved with topical and oral corticosteroids. However, there was a new widespread morbilliform eruption with dorsal oedema of his hands. A diagnosis of DRESS-like shiitake mushroom dermatitis was considered. The patient required a long course of oral prednisolone to achieve clinical and biochemical resolution of his symptoms. Our case underscores the importance of prompt recognition and management of shiitake dermatitis, especially when it presents with DRESS-like features.