Phyllodes tumors of the breast

Opinion statement Phyllodes tumor is a rare fibroepithelial neoplasm of the breast with a very variable, but usually benign, course. Formerly known as cystosarcoma phyllodes, the designation “phyllodes tumor” with appropriate qualification regarding malignant potential based on pathologic features is now the agreed-upon term. The most important diagnostic distinction is from fibroadenoma—phyllodes tumors require complete excision with free margins even when pathologic features suggest benignity because of a proclivity to local recurrence. The most important component of therapy is wide surgical excision, and mastectomy is necessary only when free margins cannot be achieved without it. Involvement of axillary nodes is rare, and axillary dissection is not indicated. The role of radiation therapy and chemotherapy is not established and has not been studied in randomized trials due to the rarity of the tumor. At present, there is no consensus that patients with high-grade phyllodes tumors of the breast will benefit from either of these modalities.