Breast lesions in a male and female with multiple myeloma

Although the breast is an uncommon primary site for extramedullary plasmacytoma, as most occur in the head and neck region, it is even more uncommon for the breast to be the site of extraosseous metastases in multiple myeloma. Extraskeletal involvement in multiple myeloma is thought to represent a true metastasis rather than autochthonous multifocal growths. Although soft tissue involvement was first recognized in 1873, breast involvement in multiple myeloma has rarely been reported. This report describes two cases of secondary breast involvement in patients with previously diagnosed multiple myeloma.