“A 72-year-old man presented to the emergency department with a 2-day history of an itchy rash on his back. On physical examination, edematous, flagellate plaques and linear patches were present across the patient’s entire back and upper buttocks. There was no adenopathy, dermographism, or mucosal involvement. What substance had the patient most likely handled and ingested before subsequently developing this rash?”

1. Phenytoin
2. Shellfish
3. Shiitake mushrooms
4. Toxicodendron radicans (poison ivy)
5. Warfarin

The correct answer is 3, Shiitake mushrooms

Source: https://www.nejm.org/image-challenge