Primary chondroblastic osteosarcoma of the breast.

Pure sarcomas of the breast are uncommon, accounting for less than 1% of primary breast malignant tumors. Mammary osteogenic sarcomas are very rare and less than 100 cases have been reported in literature. They mainly affect older and middle aged women and are highly aggressive. We report an additional case in a 56-year-old woman. Histological and immunohistological characteristics were similar to those described in other localizations. Differential diagnosis involves phyllodes sarcoma, breast metaplastic carcinoma with chondroid and osteoid differentiation, osteosarcoma of the ribs, and metastatic osteosarcoma. The prognosis is poor.