A 66-year-old man presented with a 2-day history of fevers, lethargy, polyarticular arthralgias, and a painful rash on the extensor surfaces of his lower and upper extremities. There were no other associated symptoms, including dyspnea, cough, urinary tract symptoms, or gastrointestinal symptoms.
His medical history was significant for hypertension, poorly controlled type 2 diabetes, hypercholesterolemia, and biopsy-proven autoimmune hepatitis. He was started on azathioprine for autoimmune hepatitis at a dose of 75 mg 10 days prior to his presentation after thiopurine methyltransferase activity was found to be normal. His other regular medications include aspirin, metformin, verapamil, and pravastatin.