Prognostic factors associated with solitary plasmacytoma.

Solitary plasmacytoma (SP) is a rare tumor with low incidence. The aim of this study was to investigate the clinical features, treatment strategies, and relative prognostic factors of 66 patients with SP. These patients made up 10.25% of the 644 patients with plasma cell dyscrasias treated at the Tianjin Medical University Cancer Institute and Hospital over the past 12 years. SP always presented with either solitary bone plasmacytoma (SBP) or extramedullary plasmacytoma (EMP), as determined by the location of the lesions. SBP occurred most frequently in the vertebral column and EMP in the upper respiratory tract. In addition to other factors, tumor size, serum M protein level, urinary Bence Jones protein level, and disease progression toward multiple myeloma were significantly different between the two groups (P<0.05). Larger tumor size (≥5 cm) was associated with poor prognosis of local control, multiple myeloma-free survival, overall survival and progression-free survival for SBP patients. Radiotherapy and serum β2 microglobulin <3.5 mg/L were favorable prognostic factors for local control, multiple myeloma-free survival, and progression-free survival in patients with EMP.