Postrenal transplant non-EBV multiple myeloma of donor origin.

Multiple myeloma occurring after solid organ transplantation is a rare condition, with only a few case reports found in the literature. We report a case of Epstein-Barr virus-negative, posttransplant multiple myeloma in a 67-year-old female, presenting 18 months after renal transplantation. Interestingly, fluorescence in situ hybridization analysis of the tumor revealed a Y chromosome in the majority of the cells, indicating that the neoplasm was derived from the donor kidney. To our knowledge, this represents the first reported case with these features.