A 55-year-old woman has a 3 cm breast mass. Histology shows a tumor with pushing borders, dense lymphoplasmacytic infiltrate, syncytial growth pattern, high-grade nuclei, and absent gland formation. Margins are well-circumscribed. Which molecular subtype does this tumor most commonly belong to?
- A Basal-like (triple-negative) ✓
- B Luminal B
- C HER2-enriched
- D Luminal A
Correct answer: A. Basal-like (triple-negative)
Explanation
Medullary carcinoma shows pushing borders, dense lymphocytic infiltrate, syncytial pattern, high-grade nuclei, and absent tubule formation. It is typically triple-negative (basal-like) and is associated with BRCA1 mutations. Despite high grade, it has a better prognosis than typical high-grade IDC. Luminal types are ER/PR positive and show gland formation.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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