Multiple Myeloma: A Rare Presentation as Breast Lump

Introduction: Multiple myeloma is a monoclonal immunoproliferative neoplasm of B lymphoid cells. Secondary extramedullary plasmacytoma is usually involved in advanced stages. Here we report an unusual presentation of multiple myeloma relapsing as a breast lump focusing on important findings and treatment given. Case Details: A 40-year-old woman with a past history of isolated plasmacytoma of 5th thoracic vertebra, treated with radical radiotherapy 45 Gray in 23 fractions now presented with left breast lump of 2 months duration measuring 2 x 1 cm involving the central quadrant. Ultrasonogram showed a BIRADS V lesion. A core biopsy with IHC was reported as plasmacytoma. Following this multiple myeloma work up was done. Bone marrow study showed 10% plasma cells, serum electrophoresis showed M band, raised ESR with anemia. Patient was diagnosed with Multiple Myeloma – International staging system stage III. Results: Patient was started on combination chemotherapy with 6 cycles of Bortezomib, Lenalidomide and Dexamethasone .Following treatment showed only a partial response following which the patient was started on carfilzomib. However, her disease progressed and the patient succumbed to the disease. Conclusion: Extramedullary presentation of multiple myeloma as a breast lump which itself is a rare entity despite treatment has an unfavourable course. Any patient presenting with breast lump should be evaluated carefully mostly if they have a previous history of plasmacytoma/ multiple myeloma. A proper identification of tumour pathology can evade patient from unwanted extensive surgery and thus a delay in definitive systemic treatment.