Atherosclerotic plaque: stable vs vulnerable
- Lesion
A plaque is a raised patch in the inner wall: a soft yellow core of fat and debris under a white fibrous roof.
What it is
The mature atheroma is an intimal lesion with three parts: cells (smooth-muscle cells, macrophages, T cells), matrix (collagen, elastic fibres, proteoglycans) and lipid (intracellular and extracellular, with a necrotic core). Plaques are patchy and eccentric. Their danger depends less on size than on composition: a thick cap over a small core is stable, a thin cap over a large soft core with many inflammatory cells is vulnerable to rupture.
Structure
- Gross: raised white-yellow plaques, a few millimetres to centimetres, often coalescing in the aorta; complicated plaques are ulcerated, calcified or covered by thrombus.
- H&E: fibrous cap of smooth-muscle cells and collagen; beneath it a necrotic core with cholesterol clefts, foam cells and cell debris; inflammatory cells at the shoulders.
- Advanced plaques calcify (eggshell calcification) and the underlying media thins.
- Small vessels from the vasa vasorum grow into the plaque and can bleed into it (intraplaque hemorrhage).
Stable versus vulnerable plaque
| Feature | Stable plaque | Vulnerable plaque |
|---|---|---|
| Fibrous cap | Thick, collagen-rich | Thin, collagen-poor |
| Lipid core | Small | Large and soft |
| Inflammatory cells | Few | Many macrophages and T cells |
| Typical clinical picture | Stable angina, claudication | Acute coronary syndrome, stroke |
Clinical notes
- Statins thicken the cap and reduce inflammation, which is why they prevent events beyond the change in narrowing.
Test yourself
Think of the answer, then tap the question to see it.
What are the three main components of an atheroma?
Cells (smooth muscle, macrophages, T cells), extracellular matrix (collagen, elastin, proteoglycans) and lipid (with a necrotic core).
Which artery is most often affected by atherosclerosis?
The lower abdominal aorta, followed by the coronary arteries.
Which features make a plaque vulnerable to rupture?
A thin fibrous cap, a large soft lipid core and dense macrophage inflammation with few smooth-muscle cells.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Atherosclerosis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025); Carotid Artery Stenosis (StatPearls (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.