ABSTRACT
Plasmacytomas are localized tumors containing monoclonal plasma cells that arise in bones (osseous) or soft tissue (extraosseous or extramedullary). Plasmacytomas are often seen in the setting of myeloma, where the histologic appearance of the lesions is similar to that of the marrow. Plasmacytomas are sometimes seen with no marrow abnormalities, and may be single or multiple. Multiple plasmacytomas usually tend to behave clinically like myeloma.
