Solitary plasmacytoma in the maxillary sinus: 10-year follow-up.

Solitary plasmacytoma (SP) is an uncommon form of plasma cell neoplasm occurring intraosseously or in soft tissue and presents as a single mass of monoclonal plasma cells. SP in the maxillary sinus is rare and can be misdiagnosed as other maxillary sinus tumors. The essential examinations in patients with the initial diagnosis of plasmacytoma are bone marrow biopsy, serum and urine electrophoresis, and kappa/lambda ratio (κ:λ ratio) to rule out multiple myeloma (MM). Herein, a rare case of SP in the maxillary sinus treated by surgery and localized radiation is reported. At the 10-year follow-up examination, local recurrence or disseminated development of MM were not evident.