[Nonproducing myeloma without evident bone lesion].

A 76-year-old female was admitted to our hospital because of anemia. Complete blood count was as follows: RBC 2.37 X 10(6)/microliters, Hb 7.7 g/dl, WBC 2,600/microliters, Plt 105 X 10(3)/microliters. A bone marrow aspirate revealed 40.8% plasmacytoid cells showing the characteristics of plasma cells by electron microscopy. Total serum protein was 5.4 g/dl. Monoclonal protein was not observed by electrophoresis. On immunoelectrophoresis, M-bow was not observed in the serum or in 50-fold concentrated urine. The plasma cells were negative for cytoplasmic IgG, M, A, E, D, kappa or lambda by immunoperoxidase studies. Although radiologic studies of the bones did not reveal destructive or punched out lesions, we diagnosed this case as a nonproducing myeloma and the patient responded to MP therapy. This case was considered interesting as regards the pathological entity of myeloma.