Malignant phyllodes tumor of the breast with heterologous osteosarcoma and chondrosarcomatous differentiation: A rare case report with imaging findings.

Phyllodes tumors of the breast are rare fibroepithelial neoplasms accounting for 0.3%-1.5% of all female breast tumors [1,2]. Malignant transformations occur in 10%-20% of phyllodes tumors, often in the form of stroma. Heterologous osteosarcoma and chondrosarcomatous differentiation of phyllodes tumor are extremely rare, and little is known about their imaging findings. Here, we report a rare case of a 52-year-old woman with no history of previous surgery or radiation therapy, who presented with a rapidly growing right breast mass that was diagnosed as a malignant phyllodes tumor with heterologous osteosarcoma and chondrosarcomatous differentiation. The patient underwent modified radical mastectomy.