LAUSR

BACKGROUND Because immunosuppression is necessary for kidney transplant recipients, malignant tumorigenesis of recipient organs is a concern; however, few studies have discussed the malignant alteration of transplanted grafts that have been functional for a long time. In addition, a urothelial carcinoma (UC) in transplanted kidney graft is a rare disease. CASE REPORT A 62-year-old man had end-stage renal failure 31 years ago and received a kidney transplant from his father. Acute renal failure due to obstruction of the transplanted ureter was diagnosed. Ultrasound, ureterogram, and non-enhanced computed tomography scans revealed no obvious evidence of any neoplastic lesion. We treated the obstruction and hydronephrosis with transplant ureter stenting. However, the regional lymph nodes enlarged, and it became necessary to change the ureteral stent frequently because of stent stenosis; therefore, he underwent lower transplant ureteral resection and reconstruction. Histopathology confirmed a UC with a flat and infiltrative growth pattern. The patient then underwent graftectomy including right external iliac vein resection and reconstruction; however, because of numerous metastatic nodules, radical surgery could not be performed. The patient subsequently died because of septic shock after the second surgery. CONCLUSION We report a case of an invasive UC with a flat and infiltrative growth pattern derived from a transplant kidney graft that occurred 31 years after a living-donor transplant that could not be treated immediately and was difficult to diagnose.