Case Report: Biopsy-proven acute tubular injury requiring hemodialysis during carboplatin-gemcitabine therapy

Background Carboplatin is substantially less nephrotoxic than cisplatin, and severe tubular injury during carboplatin-containing chemotherapy is uncommon. The clinicopathological spectrum of acute kidney injury (AKI) during carboplatin-based combination therapy remains incompletely characterized. Case report We describe a man with metastatic urothelial carcinoma and reduced renal reserve who developed progressive AKI after five cycles of carboplatin and gemcitabine therapy, with kidney function continuing to deteriorate after treatment cessation. Kidney biopsy demonstrated diffuse proximal tubular epithelial injury with tubular necrosis. Chronic tubulointerstitial changes were mild, with interstitial fibrosis involving <5% and tubular atrophy approximately 5% of the cortex. No histopathological evidence of thrombotic microangiopathy was identified. Clinically apparent Klebsiella pneumoniae bacteremia with concurrent urinary infection occurred approximately 1 week after biopsy-proven tubular injury had already been established. No major concomitant nephrotoxic medication or contrast exposure was identified, and there was no preceding history of substantial gastrointestinal fluid loss. Gemcitabine-associated renal toxicity and other multifactorial contributors could not be completely excluded. Progressive kidney failure ultimately required initiation of hemodialysis. The patient underwent five hemodialysis sessions over the subsequent 11 days and died before longer-term renal recovery could be assessed. Conclusion This case documents severe biopsy-confirmed acute tubular injury with necrosis occurring during carboplatin-gemcitabine chemotherapy and requiring hemodialysis. The predominantly acute tubular pattern and absence of histopathological thrombotic microangiopathy support severe tubular injury, but concomitant gemcitabine and other clinical factors preclude definitive drug-specific attribution. Close renal monitoring is warranted in patients with reduced renal reserve receiving potentially nephrotoxic chemotherapy.