Plasmacytoma can manifest as a solitary pulmonary mass, which can be accurately diagnosed through a combination of Bone scan, serum protein electrophoresis, computed tomography (CT)-guided biopsy and bone marrow biopsy. Notably, this case diagnosed with multiple myeloma (MM) with extramedullary plasmacytoma (EMP) demonstrated an exceptional treatment response to radiotherapy and proteasome inhibitor-based chemotherapy.