Breast Ultrasound Practice Test

Phyllodes tumors are fibroepithelial tumors of the breast that can behave along a spectrum from benign to malignant. They are classified into benign, borderline, or malignant based on histologic features such as stromal cellularity and atypia, mitotic activity, stromal overgrowth, and margin characteristics. Because there is an intermediate category with features between benign and malignant, describing phyllodes as a borderline between benign and malignant best fits its typical classification. And yes, it is a breast tumor, not something outside the breast.