Plasma cell myeloma associated with eosinophilia.

The association of plasma cell myeloma and eosinophilia is rare. The authors describe a 49-year-old man with plasma cell myeloma and marked absolute peripheral blood eosinophilia, 109.7 x 10(9)/L. Analysis of his bone marrow revealed cytologically atypical plasma cells that expressed monotypic IgG lambda and marked eosinophilia with normal maturation. A combination of steroids and chemotherapy resulted in a significant and sustained decrease in his absolute eosinophil count and bone marrow plasma cells. Analysis of the patient's pre-therapy serum revealed immunoreactive interleukin-3 (IL-3), but not IL-5 or granulocyte/macrophage colony stimulating factor (GM-CSF). The post-therapy serum sample was negative. Immunohistochemical analysis of the plasma cells for IL-3 and IL-5 was negative. This review of the literature has revealed five cases of plasma cell myeloma associated with eosinophilia described previously. In two patients, the eosinophilia was attributed to drug therapy. In the remaining cases, the pathogenesis of the eosinophilia was unexplained. In this case, IL-3 secreted either by the neoplastic cells at a level below detection by immunohistochemistry or by other cells in response to the presence of plasma cell myeloma may have played a role in causing the eosinophilia.