Myeloma as a Second Malignancy following AML: Is a Second Allo Equivalent to Auto?

We report a young male patient who developed plasma cell myeloma/plasmacytoma 11 years after having received an allogeneic hematopoietic cell transplantation for AML. The patient received a second transplantation from the same donor without immunosuppression and developed graft-versus-host disease (GVHD). Our observation has two aspects that warrant attention: first, insufficiency of long-term tolerance to prevent GVHD in the absence of immunosuppression and second, a stromal or genetic susceptibility to develop hematologic malignancies despite of a complete donor-type chimerism.