Invasive Ductal Carcinoma Breast MCQ — NEET PG Practice Question | NEETPGAI
Invasive Ductal Carcinoma Breast
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microscope Pathology
A 52-year-old postmenopausal woman presents with a painless lump in the upper outer quadrant of her left breast. On examination, she is noted to have dimpling of the skin with an "orange peel" appearance over the lesion. Biopsy confirms the diagnosis. The structure marked **B** in the diagram shows the characteristic gross appearance of this tumor with dermal lymphatic invasion causing the peau d'orange sign. Which of the following molecular subtypes of this tumor is associated with the worst prognosis and is most commonly linked to BRCA1 mutations?
A. Luminal A (ER+/PR+/HER2−/low Ki67)
B. HER2-enriched (ER−/HER2+)
C. Triple-negative/Basal-like (ER−/PR−/HER2−)
D. Luminal B (ER+/HER2+/− with high Ki67)
Explanation
Why Triple-negative/Basal-like is right
The structure marked B represents invasive ductal carcinoma (IDC-NST), the most common malignant breast tumor. Among the molecular subtypes, triple-negative breast cancer (ER−/PR−/HER2−), which includes the basal-like subtype, carries the worst prognosis and is strongly associated with BRCA1 mutations. This subtype lacks targeted hormone or HER2-directed therapies and typically requires chemotherapy and emerging immunotherapy (pembrolizumab). The peau d'orange sign indicates locally advanced disease (T4b), which further worsens prognosis regardless of subtype, but the question specifically asks which molecular subtype has the worst prognosis overall.
Why each distractor is wrong
Luminal A (ER+/PR+/HER2−/low Ki67): This is the most favorable subtype with the best prognosis. It is hormone-responsive and has low proliferation, making it highly treatable with endocrine therapy alone.
Luminal B (ER+/HER2+/− with high Ki67): While more aggressive than Luminal A due to high Ki67, it retains hormone receptor positivity and often HER2 positivity, allowing targeted therapies that improve outcomes compared to triple-negative disease.
HER2-enriched (ER−/HER2+): Although aggressive, HER2-positive tumors respond well to anti-HER2 therapy (trastuzumab, pertuzumab), resulting in significantly better prognosis than triple-negative disease.
High-YieldNEET PG
Triple-negative breast cancer (especially basal-like) = worst prognosis, BRCA1 association, requires chemotherapy ± immunotherapy; Luminal A = best prognosis, hormone-responsive.
NCCN Breast Cancer Guidelines; WHO Tumors of the Breast 2019
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