De novo concurrent papillary renal cell carcinoma and angiomyolipoma in a kidney allograft: evidence of donor origin

In the general population, renal cell carcinoma (RCC) is a relatively common neoplasm; however, the papillary RCC subtype is infrequent and represents only 10 to 15% of all RCC. Angiomyolipoma is a well-known common benign tumor. The occurrence of RCC in association with angiomyolipoma is a rare event, with only approximately 50 cases reported in the nontransplantation setting. In transplant recipients, RCC can develop in native kidneys, but its occurrence "de novo" in the renal allograft is very rare with an estimated incidence of less than 0.5%. We report here the case of a 39-year-old woman who underwent cadaveric renal transplantation in 1990. No lesion was observed in the allograft during the pre- and perioperative period or on early postoperative ultrasounds. No graft rejection occurred under a standard triple immunosuppressive therapy. Thirteen years later, during a routine ultrasonography, 2 solid masses were discovered in the allograft, both of them richly vascularized. She underwent allograft nephrectomy and the histologic findings revealed that one of the tumors was a chromophilic (type 1) papillary RCC (2.5 cm in diameter) and the other, an angiomyolipoma (1.5 cm). Microsatellite analysis of the allograft, as compared with the recipient peripheral blood leukocytes, demonstrated that the 2 tumors (1 malignant and 1 benign) were of donor origin. To our knowledge, this is the first report of de novo concurrent papillary RCC and angiomyolipoma in a renal allograft.