Primary mammary osteogenic sarcoma.

A 78 year-old female patient underwent a total mastectomy with axillary lymph node dissection for a primary breast osteosarcoma. Microscopically the tumor was identical to grade II skeletal osteosarcoma. Immunohistochemically no reactivity was detected, either for the epithelial markers EMA, AE1/AE3, CK8, 18, 19, or for HER-2/neu, estrogen and progesterone receptors, as well as fluorescent IN SITU hybridization for HER-2/neu. The diagnosis of this tumor fulfills certain clinicopathological criteria. Mammary osteosarcoma is usually developed in phyllodes tumors or carcinosarcomas of the breast as a result of metaplasia of the epithelial component. This rare tumor of the breast is occasionally associated with prior radiation therapy or well documented trauma. Mammary osteosarcoma is a biologically aggressive neoplasm with a 38% five-year survival rate. Surgical resection is the most effective therapy to date. Adjuvant treatment -chemotherapy or radiotherapy- has shown no clear benefit. An extensive review of the literature is also presented.