Plasmacytic tumors in the breast are extremely rare neoplasms that can mimic mammary adenocarcima. A literature review revealed approximately 43 reports worldwide of plasmacytic tumors in the breast since 1928, the majority with a synchronous diagnosis of multiple myeloma. We discuss management of a 78-year-old man with plasmacytoma in the breast who underwent a left total mastectomy and axillary lymph node dissection. This report characterizes the histologic and immunochemical characteristics of plasmacytoma in the breast and reviews the consensus on treatment. This could be the first recorded account of plasmacytomas in the breast with axillary lymph node involvement and extracapsular extension of tumor.