A 60-year-old man with stable exertional angina suffers an acute anterior myocardial infarction without any change in plaque burden on serial imaging. Histological study of the culprit coronary lesion is most likely to show which combination of features?

• A Small lipid core, thick fibrous cap, and dense collagen with minimal inflammation
• B Large lipid core exceeding 40% of plaque area, thin fibrous cap under 65 micrometers, and dense macrophage infiltration ✓
• C Concentric fibrous plaque with extensive smooth muscle proliferation and organized thrombus
• D Marked medial calcification with preservation of the internal elastic lamina

Explanation

Acute coronary syndromes result from erosion or rupture of vulnerable plaques rather than the largest stenotic lesions. Vulnerable plaques have a large lipid core occupying over 40% of the area, a thin fibrous cap less than about 65 micrometers, increased macrophages, and decreased smooth muscle, features that promote rupture and thrombosis. Stable plaques are fibrotic with thick caps and small cores, which describes option A and explains why plaque size alone poorly predicts infarction.

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.