[Coexistence of myeloma and primary myelodysplastic syndrome (MDS)].

Coexistence of myeloma and MDS was noted in a patient without history of exposure to cytotoxic drugs. A 73-year-old man was admitted because of fever and dyspnea on exertion. A complete blood count revealed macrocytic anemia with hemoglobin 7.1 g/dl, RBC 191 x 10(4)/microliters and MCV 111.2 fl. WBC was 6,000/microliters, with normal differentials. Bone marrow showed erythroid hyperplasia with M/E ratio of 1.36. There were marked tri-lineage cellular abnormalities, which included megaloblastic changes, multinucleated erythroblasts, hypersegmentation of neutrophils, giant neutrophils, and giant platelets. Ringed-sideroblasts were demonstrated in 20% of the erythroblasts. These findings were compatible with MDS. Although plasma cells accounted for only 9.7% of the nucleated marrow cells, there were many immature plasma cells with inclusion bodies, and the patient showed lambda-light chain type monoclonal gammopathy with corresponding Bence Jones protein. Immuno-histochemical staining of the bone marrow biopsy specimen revealed monoclonal growth of lambda-positive plasma cells. A punched-out lesion of the skull eventually developed. These findings suggest existence of myeloma. There have been some reports of coexistence of MDS and myeloma; supporting the idea of pluripotent stem cell origin of the disease. This is the first documentation of such a case in Japan.