IgM plasma cell myeloma with amyloidosis presenting as mammary microcalcifications

We report the case of an otherwise healthy 67-year-old woman who presented with bilateral breast masses and calcifications. Bilateral mammary biopsies showed infiltration by monoclonal neoplastic plasma cells and diffuse osseous metaplasia. Congo red stains and immunohistochemistry showed amyloid deposits. This case illustrates why multiple myeloma should be kept in mind in the diagnosis of mammary calcifications.