A phyllodes tumor of the breast is excised with a 5 mm margin and pathology reveals stromal hypercellularity, >10 mitoses per 10 HPF, and infiltrative border. What is the correct classification and recommended further management?

• A Benign phyllodes; no further surgery needed
• B Malignant phyllodes; re-excision with 1 cm margins or mastectomy ✓
• C Borderline phyllodes; re-excision to 1 cm margin
• D Malignant phyllodes; axillary dissection is mandatory

Explanation

The features — marked stromal hypercellularity, >10 mitoses/10 HPF, and infiltrative margins — classify this as a malignant phyllodes tumor. Wide excision with at least 1 cm clear margins or mastectomy is required to reduce local recurrence; a 5 mm margin is inadequate. Axillary node dissection is not routinely performed as nodal spread is rare (<5%); malignant phyllodes spreads hematogenously.

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

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Written and medically reviewed by the StethoPrep medical team.