Allopurinol-induced drug reaction with eosinophilia and systemic symptoms syndrome in a patient with previous nephrectomy: a case report

BACKGROUND: Drug reaction with eosinophilia and systemic symptoms is a rare but serious hypersensitivity reaction, typically occurring 2-8 weeks after drug initiation. It presents with rash, fever, hematological abnormalities, and multi-organ involvement, most commonly affecting the liver, kidneys, and lungs. Allopurinol is a well-recognized trigger, particularly in patients with renal impairment. This case is notable owing to the patients' previous donor nephrectomy, rather than intrinsic renal disease. CASE PRESENTATION: ) presented to the emergency department with confusion, hypotension, hypoxia, and a widespread morbilliform rash. Laboratory tests revealed severe acute kidney injury. A vasculitis screen, renal ultrasound, and computed tomography imaging of his solitary kidney were unremarkable. Further history found recent allopurinol use for gout 3 weeks prior to admission. He was diagnosed with allopurinol-induced drug reaction with eosinophilia and systemic symptoms syndrome and treated successfully with a short course of corticosteroids. CONCLUSION: This case highlights the importance of a clear medication history when assessing a patient with cutaneous and systemic symptoms. It highlights that drug reaction with eosinophilia and systemic symptoms is a rare, but an important differential to consider, particularly in patients with underlying kidney dysfunction, even in those without intrinsic kidney disease.