Fibroadenoma of the breast is classified as an intracanalicular or pericanalicular type based on the growth pattern of stroma relative to ducts. Which molecular receptor profile do these benign tumors characteristically express?

• A ER negative, PR negative, HER2 amplified
• B ER negative, PR negative, HER2 negative (triple negative)
• C Estrogen receptor (ER) positive, progesterone receptor (PR) positive, HER2 negative ✓
• D Androgen receptor (AR) positive, ER negative

Explanation

Fibroadenomas are hormone-responsive benign biphasic tumors (epithelial and stromal components) that express estrogen and progesterone receptors; they enlarge during pregnancy and lactation and often regress after menopause, reflecting hormonal dependence. The stromal component expresses PR and can contain MED12 mutations. ER/PR-negative HER2-amplified profile characterizes some invasive carcinomas. Triple-negative profile is associated with basal-like breast cancer. AR expression is a feature of some apocrine or molecular apocrine tumors.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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