Extramedullary plasmacytoma refers to plasma cell tumors that occur anywhere other than in the bone and bone marrow. This type of plasma cell tumor accounts for 4% of all plasma cell tumors and has an age of onset similar to that of multiple myeloma, with more males than females. The clinical presentation depends on the location of the extramedullary plasmacytoma. Other sites include the lower whistle, lymph nodes, spleen, skin and subcutaneous tissues, gastrointestinal tract, thyroid, and testes. In addition to the primary lesion, the disease may spread to other sites, with skeletal invasion being the most common. It is not usually associated with abnormal immunoglobulin increases, but when widespread dissemination occurs, abnormally increased monoclonal immunoglobulins or light chains may be present in blood and urine. Radiotherapy is preferred for the treatment of limited extramedullary plasmacytoma. In widely disseminated cases or relapsed cases after radiotherapy, chemotherapy should be used with the same regimen as for multiple myeloma, but the disease responds better to chemotherapy than multiple myeloma. The prognosis is better than that of multiple myeloma. About 60-70% of patients survive for more than 10 years. Those occurring in the upper whistle and limited have the best prognosis, while giant or multiple extramedullary plasmacytomas that occur outside the head and neck are prone to dissemination and have a poorer prognosis.