A rare case of DRESS/DIHS with agranulocytosis progressing to MAS in a patient with psoriatic arthritis treated with sulfasalazine

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), also known as Drug-Induced Hypersensitivity Syndrome (DIHS), is a rare hypersensitivity reaction usually presenting with eosinophilia, morbilliform rash, fever, lymphadenopathy, and internal organ involvement. We present a rare case of DRESS/DIHS in a patient with psoriatic arthritis treated with sulfasalazine and meloxicam who developed agranulocytosis, confluent macular rash, fever, lymphadenopathy and liver failure, progressing to Macrophage Activation Syndrome (MAS) — a form of hemophagocytic lymphohistiocytosis (HLH).