Malignant phyllodes tumor with chondrosarcomatous differentiation: report of a case with cytological presentation.

Malignant phyllodes tumor is a rare breast tumor with neoplastic epithelial and stromal components. The stromal component may show homologous and heterologous sarcomatous elements, including chondrosarcomatous and osteosarcomatous differentiation. Because these tumors may present with an almost exclusively sarcomatous component, it is important for the pathologist to include this entity in the diagnostic considerations of fine-needle aspirations of breast neoplasms showing sarcomatous differentiation. Following surgical excision, careful examination of the gross specimen and thorough sampling of the specimen is recommended before rendering a definitive histologic diagnosis. We describe the cytologic and histologic findings in a case of malignant phyllodes tumor with sarcomatous overgrowth showing predominantly chondrosarcomatous differentiation.