Piperacillin/Tazobactam-Induced Granulomatous Interstitial Nephritis in a Patient with Squamous Cell Lung Cancer Successfully Managed with Chemoradiotherapy.

Drug-induced acute interstitial nephritis (DI-AIN) is a common cause of acute kidney injury (AKI), particularly in patients receiving multiple medications. We report a case of AKI in a 47-year-old man with lung squamous cell carcinoma who was treated with carboplatin, paclitaxel, and tazobactam/piperacillin (TAZ/PIPC). A renal biopsy revealed acute tubulointerstitial nephritis with eosinophilic infiltration and non-caseating epithelioid granulomas. The drug lymphocyte stimulation test was positive for TAZ/PIPC, thus supporting a diagnosis of drug-associated DI-AIN. The discontinuation of TAZ/PIPC and corticosteroid therapy led to a recovery of the renal function, thereby allowing for the safe resumption of chemotherapy.