Coexistence of myeloproliferative neoplasm and plasma-cell dyscrasia.

INTRODUCTION: Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), and are characterized by clonal proliferation of hematopoietic cells in the bone marrow. There are numerous case reports and reviews reporting patients with coexisting MPN and plasma-cell disease such as multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS).

METHODS: We report 15 patients treated at our institution over a 5-year period (January 2008 to December 2012) with a diagnosis of both an MPN and MGUS or MM. We also reviewed and summarized published case reports and studies describing the coexistence of these two disease entities.

RESULTS: Most patients (12/15) had an MPN diagnosis made before or at the same time as the MGUS/MM diagnosis. Eventually, 2 patients developed a lymphoid leukemia, 1 patient developed lymphoma, and 1 patient developed acute myeloid leukemia, raising the question of whether patients with coexistence of myeloid- and lymphoid-derived neoplasms are more prone to leukemic or lymphomatous transformation. We did not find any treatment-related effect that could have contributed to the development of coexisting MGUS or MM and MPN. Of the 7 patients with an abnormal karyotype, 3 patients had trisomy 8.

CONCLUSION: At present, management strategies are aimed at treating the MPN and regularly monitoring the MGUS for transformation to an overt plasma-cell malignancy. However, for patients who develop overt MM, management is focused more on treating the myeloma and monitoring the MPN. It has not yet been definitively shown that these 2 entities arise from a common-ancestor hematopoietic stem cell.