Solitary extramedullary plasmacytoma of the breast with serum monoclonal protein: a case report and review of the literature.

A case of a solitary extramedullary plasmacytoma of the breast in a 73-year-old woman is reported. This is the second case of solitary breast plasmacytoma reported in the world literature. Plasmacytomas of the breast are extremely rare, especially those that are not associated with myelomatosis or disseminated disease. An associated monoclonal protein was present in the serum and was immunologically identical to the immunoprotein found in the tumor cells. The subject of extramedullary plasmacytomas in the breast is reviewed and discussed.