FDG PET/CT in a Case of Urothelial Carcinoma Arising From a Functional Renal Allograft

Urothelial carcinomas in renal transplant recipients usually occur in the native urinary tract but rarely in the renal allograft. We describe FDG PET/CT and contrast-enhanced CT findings in a case of high-grade urothelial carcinoma arising within the renal allograft with lymph node metastases 9 years after renal transplantation. The primary tumor appeared as an FDG-avid heterogeneously enhancing renal mass with poorly defined margins and preservation of the reniform shape mimicking centrally located infiltrative renal cell carcinoma. Multiple FDG-avid inhomogeneously enhancing ipsilateral internal and external iliac, and retroperitoneal lymph node metastases were observed.