Solitary plasmacytoma of the spine. Long-term clinical course.

The data for 19 patients with solitary plasmacytoma of the spine were reviewed with regard to clinical course and prognosis (median follow-up, 96 months). Eight patients presented with spinal cord compression. A monoclonal immunoglobulin was initially detected in seven of 15 evaluable patients. Treatment included radiotherapy (18 of 19) and/or surgery (11 of 19) and chemotherapy (eight of 19). Spinal cord compression was reversed in every patient. The expected survival rate was 85% at 10 years after diagnosis. Local recurrence or dissemination was observed in 13 patients. It occurred within 5 years of diagnosis in 11 patients and was localized (that is, local recurrence or single bone metastasis) in eight patients. It was always associated with the appearance or an increase of the M component. Dissemination frequently had a "metastatic" pattern with no diffuse bone marrow plasmacytosis. The incidence of local recurrence (five patients) and leukemia (four patients) was high. Local recurrence and/or dissemination were significantly more frequent in patients with the M component at diagnosis than in those without it (P less than 0.05; relative risk, R = 4). The effectiveness of surgery and chemotherapy combined with radiotherapy is also discussed.