Massive intramedullary globules in IgA monoclonal gammopathy associated with gastric carcinoma.

The bone marrow of a patient with IgA monoclonal gammopathy associated with gastric carcinoma was massively infiltrated with extracellular globules of varying sizes from 2 to 110 micron. These exposed globules were not found in the metastatic lesions heavily infiltrated with plasma cells, but were exclusively confined to the bone marrow. They were indistinguishable from Russell bodies and composed of monoclonal immunoglobulin (IgA, lambda). Of interest is the fact that, despite a small number of plasma cells, there was an intramedullary extensive infiltration of exposed globules. The following conditions may be related to these changes. (1) The globules were not removed rapidly by effectual phagocytosis. (2) The environment of the bone marrow may be favorable for their remaining. In our case, however, the possibility that the plasma cells around the tumor were not of the same clonal origin as the marrow plasma cells cannot be ruled out. (3) The marrow plasma cells may produce immunoglobulin more vigorously, whereas their survival time be shorter than usual. As a result, these exposed globules released on the death of the cells accumulated massively in the bone marrow.