Osteosarcoma Originating From a Malignant Phyllodes Tumor: A Case Report of a Rare Malignancy.

Fibroepithelial tumors are common in the breast; however, the frequency of malignancy is much less as compared to the epithelial counterpart. Malignant phyllodes are infrequent, and the proportion undergoing heterologous differentiation is very rare. Extensive sampling and astute examination are of utmost importance so as not to miss this lesion.