Malignant Phyllodes Tumor with Heterologous Osteosarcomatous and Rhabdomyosarcomatous Elements: A Case Report and Literature Review

Abstract

Phyllodes tumor (PT) is an uncommon fibroepithelial lesion of the breast. PT can be classified as benign, borderline, and malignant based on semi-quantitative assessment of stromal hypercellularity and overgrowth, cytologic atypia, mitotic activity, tumor border, and presence of malignant heterologous elements. PT is considered malignant by default, if malignant heterologous elements are encountered. The heterologous elements include liposarcoma, angiosarcoma, osteosarcoma, chondrosarcoma, and rhabdomyosarcoma. Malignant PT (MPT) with rhabdomyosarcomatous component is extremely rare, and only a few cases are reported. Here, we present a case of MPT with mixed osteosarcomatous and rhabdomyosarcomatous elements in a 51-year-old female, with review of the literatures and discussion of the differential diagnosis.