Which morphological feature best identifies a coronary atherosclerotic plaque as vulnerable to rupture rather than stable?

• A A dense collagenous cap rich in smooth muscle cells overlying a small core
• B A thin cap under 65 micrometers with a large necrotic lipid core exceeding 40 percent area ✓
• C Extensive calcification throughout the intima with a rigid shell
• D Concentric luminal narrowing occupying less than 50 percent of the vessel diameter

Explanation

Vulnerable plaques have a thin fibrous cap, conventionally under 65 micrometers, heavily infiltrated by macrophages and depleted of smooth muscle cells, together with a large lipid core occupying more than 40 percent of plaque area. Such plaques rupture and precipitate acute coronary syndromes. Dense calcification and a thick collagen-rich cap mark stability, and many ruptured plaques cause only mild baseline stenosis before the event.

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.