Insights of stone-induced carcinogenesis of the urinary tract through biopsies of renal pelvic lesions during lithotomy.

Introduction: Nephrolithiasis is an established risk factor for upper tract urothelial carcinoma (UTUC), but the carcinogenic mechanisms remain unclear.

Patients and methods: This study analyzed renal pelvic mucosal biopsies obtained during percutaneous nephrolithotomy (PCNL) or retrograde intrarenal surgery (RIRS) for stones, aiming to characterize the spectrum of stone-associated urothelial lesions and gain insights into lithogenic carcinogenesis.

Results: A total of 72 biopsies were performed on suspicious areas in 68 patients undergoing PCNL or RIRS. Histopathological results revealed 5 urothelial carcinoma, 1 squamous cell carcinomas, and 3 adenocarcinoma and 1 unspecified cancer, giving an overall detection rate of 13.89% for cancerous lesions. Various precursor lesions were also identified, including urothelial atypia, squamous metaplasia, and intestinal metaplasia. This study provides representative CT images of these stone-associated malignant tumors of the renal pelvis, and gives preliminary evidence that these tumors are frequently demonstrating squamous or glandular differentiation.

Conclusion: The identification of diverse precursor lesions supports the hypothesis that calculi induce stepwise oncogenic transformation, potentially via chronic inflammation and urothelial injury. Further research on lithogenic carcinogenesis may elucidate therapeutic targets for this aggressive subset of UTUC.