Multiple myeloma after cardiac transplantation: an unusual form of posttransplant lymphoproliferative disorder.

Published reports of posttransplant myeloma are extremely uncommon (three cases); to the best of our knowledge there have been no reported cases in cardiac transplant recipients. We are also unaware of any report of Epstein-Barr virus (EBV) genome studies in posttransplant myeloma. We report here the case of a 48-year-old man who developed multiple myeloma 1.5 years after cardiac transplantation. The results of a serum analysis were consistent with past EBV infection. Biopsy of a skull lesion showed a monomorphous population of malignant immature plasma cells that showed monotypic cytoplasmic staining with antibodies to lambda light chains. A monoclonal immunoglobulin heavy chain gene rearrangement was detected by polymerase chain reaction (PCR). Both EBER-1 in situ hybridization and EBNA-1 PCR were negative for the EBV genome. Cyclosporin withdrawal was followed by transient clinical and biological improvement, but the tumor later progressed and eventually stabilized in response to treatment with dexamethasone alone. This case illustrates that posttransplant lymphoproliferative disorders (PTLPDs) encompass not only EBV-positive but also EBV-negative cases and not only lymphomas but also myelomas.