Association between carcinosarcoma and the transplanted kidney.

Background: Renal carcinosarcoma is a rare tumor with 12 reported cases in the world literature. To our knowledge, carcinosarcoma of a renal allograft has not been reported to date.
Case Report: A multifocal urothelial carcinosarcoma of a transplanted kidney in a 49-year-old woman is described. Genomic analysis of the extracted nuclei of all the neoplastic cells showed uniformly XY genotype proving the transplant origin of the tumor.
Results: The carcinogenic role of immunosuppressive medications in kidney-transplanted patients is reported in the literature. In this case, immunosuppression may have promoted the carcinosarcoma.
Conclusion: Renal transplant patients should be monitored for the development of malignancy in the allograft and elsewhere.