Digital Atlas of Breast Pathology by Meenakshi Singh, MD © - Department of Pathology, Stony Brook University Medical Center

Fibroadenoma with phylloidal features and mild stromal atypia
Benign phyllodes tumors closely resemble fibroadenomas. They have an exaggerated intracanalicular growth with a leaf-like pattern. The mesenchymal component has an increased cellularity with minimal pleomorphism and/or low mitotic activity. This fibroadenoma has phylloidal features because of the mild stromal atypia and increased stromal cellularity in periductal regions.