Solitary bone plasmacytoma and extramedullary plasmacytoma.

Solitary bone and extramedullary plasmacytomas are rare plasma cell proliferative disorders. Their diagnosis is based on histologic confirmation of monoclonal plasma cell infiltration of a single disease site and on the exclusion of systemic myeloma. For both entities, the treatment of choice is localized radiotherapy. With modern radiotherapy and with a total dose of at least 4000 cGy, the risk for local recurrence is less than 5%. There is no role for systemic chemotherapy in the management of these disorders. Approximately 30% of patients with solitary bone plasmacytoma (SBP) remain disease-free for several years; some of these patients may be cured. Patients with the best prognosis are those in whom the monoclonal protein disappears by 1 year after radiotherapy. The prognosis of patients with solitary extramedullary plasmacytoma (SEP) appears to be better than for patients with SBP because approximately 70% of patients with SEP remain disease-free at 10 years. With more sensitive staging procedures, the diagnosis of SBP and SEP may become less common, but the number of patients with prolonged stability and cure may increase.