Drug-induced acute interstitial nephritis and vasculitis or vasculary rejection in renal allografts.

We describe a patient who sought treatment for acute renal allograft dysfunction 2 weeks after renal transplantation. Renal allograft biopsy (RAB) showed intimal arteritis, severe interstitial infiltration with a few eosinophils, and severe tubulitis. Pathologic diagnosis was acute rejection (grade 2b- Banff 93); however, another clinical diagnosis, drug-induced acute interstitial nephritis (AIN), was not excluded. Before the RAB, his trimethaprim-sulfamethoxazole (TMP-SMZ) treatment was discontinued. Renal function began to improve on biopsy day without antirejection therapy. Recovery of renal function without antirejection treatment and discontinuation of TMP-SMZ shows that renal pathology might be related to drug-induced dysfunction and drug-induced AIN and vasculitis. After 5 years, the patient and his renal allograft function are both well.