Primary Renal Cell Carcinoma in a Transplanted Kidney: Genetic Evidence of Recipient Origin

BACKGROUND: Primary renal cell carcinoma (RCC) is the most frequent kidney cancer. In renal transplant patients, RCC more commonly arise in the native kidneys, whereas allograft involvement has been just occasionally reported. In these latter cases, a graft origin of tumor cells should be considered and other recipients from the same donor should be investigated. So far, genetic studies to trace the origin of cancer cells have always confirmed the donor origin of these tumors. METHODS: A 58-year-old man developed an RCC in the grafted kidney 14 years after transplantation. Histologic and immunohistochemical studies diagnosed a clear cell RCC with sarcomatoid changes. A nine microsatellite DNA assay was used to compare renal tumor cells with donor's (graft parenchyma) and recipient's (lymph nodes and blood) cells. RESULTS: Of the nine microsatellites analyzed, four turned out to be noninformative and the other five (D1S2734, D1S214, D1S199, D19S219, and Humara) showed different band profiles in donor's and recipient's cells DNA. Tumor and blood profile matching confirmed the recipient origin of neoplastic cells. CONCLUSIONS: We report the first case of a grafted-kidney RCC whose recipient's cell origin has been proved by microsatellite analysis. An origin from the recipient's kidney or bone marrow stem cells is proposed as the more plausible hypothesis.