A rare case report of extra medullary plasmacytoma involving the posterior mediastinum coexistent with multiple myeloma

Abstract

Introduction: Plasma cell neoplasms are characterized by the clonal proliferation of plasma cells. They include monoclonal gammopathy of undetermined significance, multiple myeloma, and solitary osseous or non-osseous plasmacytoma. Multiple myeloma is characterized by the proliferation of plasma cells in the bone marrow and can result in extensive skeletal destruction, whereas plasmacytoma is characterized by the proliferation of plasma cells restricted to one area of the body. Case Report: A 65-year-old female presented for workup of incidental mass noted on computed tomography (CT) of the chest. She was noted to have posterior mediastinal plasmacytoma with elevated IgA and free lambda light chains on serum electrophoresis. She subsequently underwent the bone marrow biopsy which revealed multiple myeloma. The patient was diagnosed with IgA lambda multiple myeloma with a posterior mediastinal plasmacytoma with multiple bony lesions. She underwent radiotherapy with interval resolution of posterior mediastinal mass and currently on chemotherapy for multiple myeloma. Conclusion: Once plasmacytoma is diagnosed, a further workup for multiple myeloma is needed as treatment is entirely different for both types of plasma cell neoplasms.