Phyllodes tumors with and without fibroadenoma-like areas display distinct genomic features and may evolve through distinct pathways

Histologic features of phyllodes tumors (PTs) with and without fibroadenoma (FA)-like areas included in this study. Representative micrographs of a malignant PT with FA-like areas a, displaying areas of marked stromal cellularity and cytologic atypia b intermingled with FA-like areas showing intracanalicular growth pattern, low stromal cellularity and no cytologic atypia c. Representative micrographs of a malignant PT without FA-like areas d, displaying infiltrative borders, prominent stromal cellularity e, marked cellular atypia and numerous mitoses f. Scale bars in a and d, 100？μm, b, c, and f, 20？μm, and e, 50？μ