A 42-year-old woman presents with a 3 cm breast lump. Core biopsy confirms a phyllodes tumor with the following histological features: >10 mitoses/10 HPF, marked stromal cellularity, infiltrative margins, and stromal overgrowth. This tumor is classified as:
- A Benign phyllodes tumor — wide local excision with 1 cm margins
- B Malignant phyllodes tumor — wide excision with ≥1 cm margins; mastectomy if margins not achievable ✓
- C Borderline phyllodes — adjuvant radiation recommended
- D Malignant phyllodes — sentinel node biopsy mandatory
Correct answer: B. Malignant phyllodes tumor — wide excision with ≥1 cm margins; mastectomy if margins not achievable
Explanation
Malignant phyllodes tumors are characterized by >10 mitoses/10 HPF, marked stromal cellularity, infiltrative margins, and stromal overgrowth. Management requires wide excision with ≥1 cm margins; simple mastectomy is performed when clear margins cannot be achieved. Axillary lymph node dissection or sentinel node biopsy is NOT routinely performed as lymphatic spread is rare (phyllodes spread hematogenously). Adjuvant radiation may be considered for R1/R2 resections or recurrent disease. Borderline phyllodes have 5-9 mitoses/10 HPF.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.