[Clinico-pathological studies of tumor-forming type of multiple myeloma]

Among 49 myeloma cases studied, 31 lesions were found to develop into extramedullary tumors in 8 cases and 22 lesions were found to develop into skeletal tumors in 14 cases. The locations of the extramedullary tumors were the lymph nodes, subcutaneous tissue, liver, kidney, stomach, and pancreas. The location of the skeletal tumors was the ribs, thoracic spines, and skull. These tumors were diagnosed as plasmacytomas by biopsy and/or touch- or aspiration cytology. The biological and clinical characteristics of the tumor-forming type compared with the non-tumor-forming type, were their occurrence in younger patients, a higher incidence of Bence-Jones proteinuria, more marked bone lesions and almost normal renal function. Concerning the monoclonal immunoglobulin (M-component) of the tumor-forming type, there were more of the Bence-Jones type and fewer of the IgA type than in the non-tumor-forming type. No relationship between tumor-formation and prognosis was seen.