Myeloproliferative disorders and nonmyelomatous paraprotein. A study of five patients and review of the literature.

Five patients with myeloproliferative disorders and paraprotein are reported. The diseases included acute myelomonocytic leukemia, chronic myeloid leukemia, sideroblastic anemia with excess of blasts, polycythemia vera and myelofibrosis. In four cases, the paraprotein was of the IgG k type and in one, IgM k. No evidence of multiple myeloma or excessive plasmacytosis was noted. The literature records 19 other myeloid disorders with this unusual association. Although the pathogenesis remains unclear, three possible explanations are suggested: disturbance of the pluripotent stem cell resulting in a combined myeloplasmatic disorder, coexistence of two diseases, or a fortuitous association.