Malignant cystosarcoma phyllodes tumor of the breast mainly composed of chondrosarcoma: a case report.

Sarcoma of the breast is a very rare occurrence. We experienced a patient with malignant phyllodes tumor, in which a chondrosarcomatous element constituted 90% of the tumor volume. That bone or cartilage may be present in mammary neoplasms has been known for a long time. Most mammary tumors with areas of chondroid metaplasia show a benign histologic appearance. Cystosarcoma phyllodes displaying a chondrosarcomatous element is very rare. The results obtained by echographic and pathologic examinations strongly suggest that the chondrosarcomatous element originates from the fibrous stroma.