plaque
Meaning of plaque: One word, three unrelated meanings: a skin lesion, a fatty deposit inside an artery, and the bacterial film that coats teeth.
Definition of plaque
Plaque names several unrelated things that share only the idea of a flattened deposit or patch. On skin it is a raised, flat-topped lesion wider than about a centimeter. In an artery it is a deposit of fat, cholesterol, calcium and inflammatory cells built up inside the vessel wall. On teeth it is a sticky film of bacteria. Context decides which is meant.
What is a plaque on the skin?
Dermatology uses exact words for the shape of a lesion, and plaque is one of them. A plaque stands slightly above the surrounding surface, has a broad flat top, and measures more than about a centimeter across. A papule is the same kind of raised bump but smaller. A skin patch is flat rather than raised, and a macule is a small flat spot. Psoriasis is the classic plaque-forming condition, producing thickened scaly areas most often over the elbows, knees and scalp. Eczema, lichen planus and some skin lymphomas form plaques as well, so the word narrows the appearance without naming a cause on its own.
How is arterial plaque different?
Inside a blood vessel, plaque is not a surface feature at all. It accumulates within the wall of the artery over years and contains fat, cholesterol, calcium, cellular debris and inflammatory cells, usually capped by a layer of fibrous tissue. It narrows the channel the blood flows through and stiffens the vessel, the process called atherosclerosis. Narrowing on its own limits flow to whatever the artery supplies. The larger danger is rupture: if the fibrous cap tears, a clot forms at the torn surface and can block the vessel suddenly, which is the usual mechanism behind a heart attack or many strokes.
Which sense is meant?
The surrounding words settle it every time, because the four common senses belong to separate specialties and describe structures with nothing in common.
| Sense | What it is | Where the word appears |
|---|---|---|
| Skin plaque | Raised, flat-topped lesion over about a centimeter wide | Dermatology notes, rash descriptions |
| Arterial plaque | Fatty, fibrous deposit within a vessel wall | Cardiology and vascular imaging |
| Dental plaque | Soft bacterial biofilm on tooth surfaces | Dentistry and oral health |
| Amyloid plaque | Clump of misfolded protein between brain cells | Neurology and dementia research |
Dental plaque deserves a note of its own because it is the sense most people meet first. It is a biofilm, a living layer of bacteria and the sticky material they secrete, and it re-forms on teeth continuously. Bacteria in the film turn sugars into acid that dissolves enamel, and the same film inflames the gum margin. Left undisturbed it takes up minerals from saliva and hardens into tartar, also called calculus, which brushing no longer removes.
Used in a sentence
Imaging of the vessel revealed plaque narrowing the artery's lumen.
Good to know
Skin, arterial and dental plaque are unrelated structures that share only a name, so the surrounding clinical context, rather than the word itself, indicates which one is meant.