Solitary plasmacytoma of bone and soft tissue

Between 1962 and 1978, 15 patients presenting with a solitary plasmacytoma were treated with curative intent by radiotherapy alone at the University of Florida. Criteria for admission to this study were: 1) a biopsy-proven, apparently solitary focus of plasmacytoma; 2) bone marrow biopsy showing less than 10% plasma cells; and 3) no evidence of disseminated disease. In 9 patients the primary site was osseous and in 6 patients extramedullary; 5 of the 6 extramedullary lesions were located in the upper respiratory passages. Two of the 6 extramedullary plasmacytomas progressed to multiple myeloma at 2 and 7 months. The remaining 4 patients have been disease free for periods ranging from $\text{2}\text{2}\text{3}$ years to over 16 years. Of the 9 patients with osseous lesions, 3 developed multiple myeloma in 3–23 months and one developed a solitary second bone lesion at 9 years. One patient with a large sacral lesion developed a local recurrence following an initial radiation dose of 3000 rad. The recurrence was re-treated with radiation, and local control was obtained. No other local failures occurred. This study presents a detailed analysis of the time-dose relationship required for local control, based on a study of our own patients and a review of the literature.