Multiple myeloma derived from a kidney transplant donor who also developed myeloma after kidney donation.

Patients who undergo kidney transplantation are at increased risk of cancer due to the long-term use of immunosuppressive treatment. Postrenal transplant cancers usually originate from recipient cells, but donor-related cancers have been rarely reported. We report the case of 49-year-old woman who developed multiple myeloma of donor origin 7 years after kidney transplantation. The donor was the mother of the recipient and also developed multiple myeloma 1 year after kidney donation. The diagnosis of multiple myeloma was based on IgG lambda monoclonal protein and the infiltration of plasma cells in bone marrow. The renal biopsy did not reveal plasmacytoma in the transplanted kidney. Epstein-Barr virus DNA load was negative in peripheral blood. The patient responded to lenalidomide and dexamethasone, and subsequently received autologous stem cell transplantation. Donor chimerism was detected in the recipient marrow by short tandem repeat analysis; however, studies of Ig gene rearrangement were inconclusive due to insufficient DNA quality. The chromosomal abnormalities in the two myelomas were different. This case suggests that donor cells with myeloma-initiating potential can be transferred to a recipient via a renal graft and can lead to the development of donor-derived multiple myeloma in the recipient under immunosuppression.