A Formidable Foe: BK Virus, an Association with Early Cancer Development: A Case Report

Introduction: Urothelial cancer of the bladder is the most common malignant neoplasm of the urinary system. Kidney transplant recipients have a significantly higher risk of urothelial malignancy compared to the general population; it typically presents about 8.5 years after transplantation. BK-polyoma virus (BKPyV) is a well-established cause of urothelial malignancy in kidney transplant recipients. We present a rare case of urothelial carcinoma of the urinary bladder diagnosed three months after kidney transplantation. Case Description: A 71-year-old woman underwent a deceased donor kidney transplant (DDKT) due to end-stage renal disease secondary to diabetes mellitus. The intraoperative cystoscopy for ureteral anastomosis showed no evidence of growth in the urinary bladder. However, one month later, at the time of the ureteral stent removal, a papillomatous growth was noted near the site of ureteral anastomosis. Subsequently, a repeat cystoscopy and excisional biopsy revealed urothelial cancer. Concurrently, elevated levels of plasma BKPyV were noted, which continued to rise despite the reduction in immunosuppression. The tumor tissue was positive for SV40 stain, suggesting a possible causal correlation with BKPyV identified in the cancer tissue. Discussion: Despite the widely known presentation of BKPyV viremia in kidney transplant patients, the presentation of malignancy is typically delayed. This case highlights the need for a high index of suspicion for any bladder lesion in post-transplant patients with elevated levels of BKPyV. Early diagnosis with biopsy and SV 40 immunostaining is crucial for improved patient outcomes.