Borderline Phyllodes Breast Tumors: A Comprehensive Review of Recurrence, Histopathological Characteristics, and Treatment Modalities

Phyllodes tumors account for 2–3% of all fibroepithelial breast tumors and less than 1% of all breast cancers. These tumors are categorized into benign, borderline, or malignant based on cellular atypia, mitotic activity, and stromal overgrowth. Surgical excision with clear margins, ideally greater than 1 cm, is the primary treatment for phyllodes tumors to ensure effective local control. Preoperative diagnosis is challenging due to the clinical and radiological similarities between phyllodes tumors and fibroadenomas. The efficacy and role of adjuvant treatments remain subjects of ongoing debate and investigation. Borderline phyllodes tumors exhibit biological characteristics that straddle the line between benign and malignant, presenting significant clinical and surgical management challenges. Given the rarity of this specific subgroup and the ambiguity of the risk of recurrence or progression to malignant phyllodes, this narrative review aims to provide a comprehensive overview of the recurrence risk associated with these tumors.