[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Blood vessels](https://durgical.com/en/general-pathology/areas/vessels/) › Atherosclerotic plaque: stable vs vulnerable

# 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.

Updated Nov 12, 2026

## Key points

- Order of involvement: lower abdominal aorta, coronary arteries, popliteal arteries, internal carotids, circle of Willis.
- Fatty streak: flat, yellow, foam cells; not obstructive; may or may not progress.
- Fibroatheroma: fibrous cap + necrotic lipid core (cholesterol clefts, foam cells, debris) + shoulder region + neovascularisation.
- Vulnerable plaque: thin cap, large necrotic core, many macrophages, few smooth-muscle cells.
- Most ruptured plaques were not severely stenotic before the event.

## 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.

## Memory aid

Judge a plaque by its roof, not its size: thick roof sleeps, thin roof cracks.

## 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.

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## Elsewhere in DurgiPedia

- [Blood vessels: artery, vein and capillary layers](https://durgical.com/en/histology/blood-vessels-artery-vein-and-capillary-layers/)

## Connections

## Related 4

- [How an atheroma forms: the response-to-injury model step by step](https://durgical.com/en/general-pathology/how-an-atheroma-forms-the-response-to-injury-model-step-by-step/)
- [Consequences of atherosclerosis](https://durgical.com/en/general-pathology/consequences-of-atherosclerosis/)
- [Pathologic calcification: dystrophic vs metastatic](https://durgical.com/en/general-pathology/pathologic-calcification-dystrophic-vs-metastatic/)
- [Intracellular accumulations: cholesterol, proteins, hyaline, glycogen](https://durgical.com/en/general-pathology/intracellular-accumulations-cholesterol-proteins-hyaline-glycogen/)

## Related conditions 5

- [Atherosclerosis and dyslipidaemia](https://durgical.com/en/conditions/atherosclerosis-and-dyslipidaemia/)
- [Stable angina](https://durgical.com/en/conditions/stable-angina/)
- [Carotid artery stenosis](https://durgical.com/en/conditions/carotid-artery-stenosis/)
- [Peripheral artery disease](https://durgical.com/en/conditions/peripheral-artery-disease/)
- [Abdominal aortic aneurysm](https://durgical.com/en/conditions/abdominal-aortic-aneurysm/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

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](https://medlineplus.gov/ency/article/000171.htm) (MedlinePlus, US National Library of Medicine, 2025); [Carotid Artery Stenosis](https://www.ncbi.nlm.nih.gov/books/NBK442025/) (StatPearls (NCBI Bookshelf), 2025).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/atherosclerotic-plaque-stable-vs-vulnerable/