Primary osteosarcoma of the breast.

Primary osteosarcoma of the breast is a rare malignant tumor. We report on an 80-year-old woman who presented with a right breast lump and a mammogram suggestive of carcinoma. The lesion was excised and histological features of the tumor were consistent with primary osteosarcoma. Due to insufficient resection margins, segmental mastectomy was performed to establish clear margins and failed to show any remaining tumor. There was no evidence of a separate primary tumor, and a metastatic work-up was unrevealing. We determined that primary treatment with segmental mastectomy was adequate and no further treatment was necessary. She remains disease free at 15 months.