Can BKPyV Infection Affect Neoplasm Transformation Among Kidney Transplant Recipients? A Case Series Study Report

<b>Background:</b> There is a great deal of knowledge regarding the development of polyomavirus-associated nephropathy and polyomavirus-associated hemorrhagic cystitis in transplant recipients with active BKPyV infection. However, recent studies have revealed a potential association between BKPyV reactivation and certain malignancies, including transitional cell carcinoma, malignant melanoma, colorectal cancer, and prostate cancer. This study aimed to identify a potential link between BKPyV infection and oncogenic transformation in kidney transplant recipients. <b>Methods:</b> Presentation of a case series of kidney transplant recipients diagnosed with polyomavirus-associated nephropathy who developed neoplasms after transplantation. <b>Results:</b> Positive immunohistochemical reactions confirmed the presence of polyomavirus large T antigen in tissue samples from all three patients' cancers. Furthermore, a case of chromophobe renal cell carcinoma presenting BKPyV proteins in cancer cells was observed for the first time in the literature. <b>Conclusions:</b> BKPyV reactivation was found to be associated with the development of both urothelial cancer, which originates directly from the BKPyV-infected site, and colorectal cancer.