Breast phyllodes tumors are uncommon biphasic, fibroepithelial neoplasms which account up to 1% of all primary breast tumors.These rare tumors have a propensity to recur and ability to metastasize .The behavior of phyllodes tumor in all forms (benign, borderline, and malignant) is unpredictable.This book discusses the fundamental basis in detecting the bizarre behavior and the treatment options of this challenging breast tumor type.