A 22-year-old woman presents with a painless, firm, well-demarcated, rubbery 2 cm breast lump that moves freely on palpation. Biopsy shows a biphasic proliferation of both epithelial and stromal components with intracanalicular growth pattern. What is the diagnosis, and what hormonal influence promotes its growth?
- A Phyllodes tumour; progesterone-driven stromal overgrowth
- B Fibroadenoma; oestrogen-stimulated stromal and glandular proliferation ✓
- C Intraductal papilloma; prolactin-driven ductal hyperplasia
- D Sclerosing adenosis; lobular proliferative response to postpartum hormones
Explanation
The clinical and histological features describe a classic fibroadenoma — the most common benign breast tumour in women under 30. It is a biphasic tumour with both epithelial (ducts/lobules) and specialised intralobular stromal components; the intracanalicular pattern shows compressed, elongated ducts surrounded by proliferating stroma. Oestrogen stimulates growth (fibroadenomas enlarge with pregnancy and OCP use, involute post-menopausally). The distinction from phyllodes tumour is important: phyllodes shows leaf-like fronds, stromal hypercellularity, and mitotic activity.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.