Abstract
Phyllodes tumor is a rare fibroepithelial breast mass that typically manifests as a painless, multinodular breast tumor. One characteristic feature of phyllodes tumors is that they tend to increase in size rapidly over time unlike fibroadenomas. On ultrasound, they typically appear as a hypoechoic solid mass that may contain cystic components. On mammography, they appear hyperdense. Definitive diagnosis requires biopsy, with histological findings of leaf-like architecture and stromal cellularity. This report presents a case of giant malignant phyllodes tumor in a 53-year-old female who underwent right mastectomy and provides an overview of its clinical presentation, diagnostic workup, radiologic imaging findings, and management.