Localized primary amyloid tumor associated with osseous metaplasia presenting as bilateral breast masses: cytologic and radiologic features.

This report details the cytologic features of primary localized amyloid tumor of the breast presenting as bilateral breast masses in a 72-yr-old woman. Clinically and radiographically, the masses simulated metastatic or multifocal carcinoma. Fine-needle aspiration revealed irregular globules of acellular amorphous material and numerous multinucleated giant cells resembling granulomatous inflammation. Histology confirmed amyloid tumors with a foreign-body giant cell reaction in response to amyloid and foci of osseous metaplasia. Subsequent clinical workup included a serum electrophoresis and immunofixation which showed a small IgG kappa monoclonal protein. Urine immunofixation was negative for Bence Jones protein. Bone marrow examination revealed no evidence of a plasma cell dyscrasia. To date the patient has not developed clinical or laboratory evidence of systemic amyloidosis or multiple myeloma. Amyloidosis involving the breast and specifically localized primary amyloid tumors of the breast are rare and infrequently reported entities. To our knowledge, osseous metaplasia within isolated primary amyloid tumors of the breast has not been reported. We present this unusual case to illustrate the intratumoral calcification patterns mimicking carcinoma and to characterize the cytologic features. Emphasis is placed on the inclusion of amyloidosis in the differential diagnosis of breast masses.