Coincidental polycythemia vera and multiple myeloma: case report and review.

Polycythemia vera (PCV) and multiple myeloma are both clonal disorders of hematopoietic stem cells. The simultaneous occurrence of these diseases in an individual patient is rare. A case of synchronous PCV and smoldering myeloma is presented and the literature is reviewed. The issues of clinical importance in this unusual case include the mechanisms of anemia in multiple myeloma, the difficulty in using anemia as a parameter on which to base the initiation of therapy for myeloma, and the risks of treatment-induced leukemia and myelodysplasia.