Abstract: TH-PO1046
High-Grade Urothelial Carcinoma After BK Virus Nephropathy in an En Bloc Kidney Allograft from a Pediatric Donor
Session Information
- Transplantation: Clinical - Outcomes, Malignancy, and Pathology
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Transplantation
- 2002 Transplantation: Clinical
Authors
- Jabbar, Danish, Royal Free London NHS Foundation Trust, London, England, United Kingdom
- Elshayeb, Mohamed Mohsen, Royal Free London NHS Foundation Trust, London, England, United Kingdom
- Dunn, James, Royal Free London NHS Foundation Trust, London, England, United Kingdom
- Salama, Alan D., Royal Free London NHS Foundation Trust, London, England, United Kingdom
Introduction
We report a rare case of high-grade UC in a pediatric en-bloc allograft more than 10 years after transplant, following severe BK viremia and biopsy-proven BK virus nephropathy (BKVN).
Case Description
A 37-year-old woman with ESKD of unknown etiology received a deceased-donor pediatric en-bloc kidney transplant in 2014.She received induction immunosuppression with basiliximab/methylprednisolone. Early complications included urinary leak, E. coli bacteremia, and hydronephrosis requiring nephrostomy/stenting.
Later in 2014, concurrent BK and CMV viremia developed. BK viral load peaked at ~800,000 copies/mL in 2015 with biopsy-proven BKVN, then resolved by 2018 after immunosuppression reduction. Ten years post-transplant, she developed graft dysfunction with creatinine 600 µmol/L and hydronephrosis. Initial imaging suggested clot retention, with transient improvement after nephrostomy. Recurrent dysfunction with BK viremia (~7,000 copies/mL) prompted repeat imaging which showed a vascularized 50×23×41 mm lesion.PET scan showed a hypermetabolic mass from lower pole to pelvi-ureteric junction without metastases. Urine cytology suggested high-grade UC and cystoscopy showed normal bladder .
Transplant nephroureterectomy done in May 2025,revealed high-grade papillary UC invading muscularis propria with staging pT3N0M0.
Tumor cells showed diffuse nuclear SV40 positivity (Figure 1); C4d was negative. Margins were clear. Immunosuppression was stopped, she was transitioned to hemodialysis.Recent Surveillance scans in March/2026 showed no recurrence.
Discussion
Although tumor BK DNA integration or large T-antigen mRNA testing was not performed, the allograft renal pelvis location, prior BKVN, recurrent viremia, and diffuse tumor-cell SV40 positivity support possible BKPyV-associated oncogenesis.
Take-away lesson: Recurrent or late BK viremia with clot-like obstruction,hydronephrosis and graft dysfunction should prompt evaluation for urothelial malignancy.
SV40 immunohistochemistry supporting BKPyV-associated tumor biology