Phyllodes tumor of the breast

Definition

A rare fibroepithelial tumor of the breast characterized by a painless, circumscribed, firm mass potentially arising in any part of the breast, histologically showing a prominent intracanalicular growth pattern with leaf-like stromal fronds, capped by luminal epithelial and myoepithelial cell layers, accompanied by stromal hypercellularity. The tumor may be benign, borderline, or malignant.