Which subtype of phyllodes tumor of the breast is characterized by stromal overgrowth, high mitotic rate (>10/10 HPF), and infiltrative margins, conferring the highest risk of distant metastasis?

• A Benign phyllodes
• B Borderline phyllodes
• C Giant fibroadenoma with stromal atypia
• D Malignant phyllodes ✓

Explanation

Malignant phyllodes tumors exhibit stromal overgrowth (stroma without epithelium in at least one low-power field), high mitotic count, marked nuclear pleomorphism, and infiltrative borders. They metastasize hematogenously to lungs and bones but rarely spread to axillary nodes, so lymphadenectomy is not routinely indicated. Wide local excision with clear margins (≥1 cm) is the surgical standard; adjuvant radiation is considered for close margins.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.