Introduction Plasmacytoma is a rare neoplastic disorder caused by the abnormal monoclonal proliferation of mature B cells, accounting for approximately 10% of all hematological tumors.1 Plasmacytomas are clinically and pathologically classified into three types: multiple myeloma (MM), solitary bone plasmacytoma (SBP), and solitary extramedullary plasmacytoma (SEP).2 SEP is an extremely rare soft tissue mass composed of monoclonal plasma cells, accounting for 3–4% of all plasmacytomas.
