Identification of donor melanoma in a renal transplant recipient.

A patient with chronic renal failure received a closely matched cadaveric kidney. Approximately 3 months after transplantation, the patient developed a metastatic malignant melanoma. A large retroperitoneal mass consisting of large pleomorphic polygonal neoplastic cells was found close to the donated kidney. This tumor was diagnosed as a malignant melanoma. DNA analysis of this tumor, the donated kidney, and the recipient indicated that the melanoma originated from the donor. Although this is not the first report of a donated melanoma, it is the first report of definitive DNA analysis of the origin of the malignant cells.