[A CASE OF RENAL CELL CARCINOMA IN THE KIDNEY ALLOGRAFT 16 YEARS AFTER RENAL TRANSPLANTATION].

A man in his 70s underwent ABO-incompatible renal transplantation 19 years ago at another hospital for end-stage renal failure due to IgA nephropathy. The immunosuppressive regimen included tacrolimus 4mg/day, mycophenolate mofetil 500 mg/day, and prednisolone 5 mg/day. Renal function remained stable post transplantation, withserum creatinine levels ranging from 1.0 to 1.2 mg/dl. Contrast-enhanced computed tomography performed for the sudden onset of the aortic dissection showed a tumor 14 mm in diameter on the ventral side of the kidney allograft, with early contrast enhancement. The tumor was less than 10 mm deep into the renal cortex. Based on these findings, the patient was diagnosed with cT1aN0M0 renal cell carcinoma in a kidney allograft, and an open partial nephrectomy was performed without renal ischemia. Histopathological examination demonstrated clear cell renal cell carcinoma, WHO/ISUP Grade 2, without vascular invasion, and negative surgical margins. Postoperatively, renal function was preserved, and no recurrence has been observed during a 2-year follow-up period.