A 40-year-old woman presents with a 4 cm breast mass. Core biopsy shows a biphasic tumor with benign glands and a cellular stroma forming leaf-like projections. The stromal mitotic count is 2 per 10 high-power fields. What is the diagnosis?

• A Fibroadenoma
• B Borderline phyllodes tumor
• C Benign phyllodes tumor ✓
• D Malignant phyllodes tumor

Explanation

The leaf-like architecture and stromal cellularity define a phyllodes tumor. Mitotic count <5/10 HPF classifies it as benign. Borderline phyllodes tumors have 5-9 mitoses/10 HPF, and malignant phyllodes tumors have ≥10 mitoses/10 HPF. Fibroadenoma lacks true leaf-like projections and has a less cellular stroma.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.