Fluorescence In Situ Hybridization for the Origin of De Novo Renal Cell Carcinoma in a Kidney Allograft: A Case Report.

ABSTRACT Background We present a rare case of de novo renal cell carcinoma that developed in an allograft kidney 14 years after transplantation. Case report A 39-year-old man underwent living donor kidney transplantation from his mother. After 14 years, routine screening ultrasonography revealed a solid mass of 30-mm diameter in the kidney allograft. Partial nephrectomy was performed by clamping the renal artery under in situ cooling. Tissue histology revealed clear cell carcinoma with negative surgical margins. We explored the tumor's genetic origin using fluorescence in situ hybridization to analyze the X and Y chromosomes of the tumor cells. Postoperative hemodialysis was avoided, and the patient's serum creatinine level remained stable. Conclusions Fluorescence in situ hybridization clearly indicated that the tumor originated from the donor and that the tumor vasculature originated from the recipient. The patient recovered well and remains without any tumor recurrence.