Plaque is a word that has different meanings in different contexts. This is about the skin lesion referred to as plaque.
In the context of the skin (as opposed to its other meaning in dentistry), the word plaque refers to a type of raised lesion whose surface area is much larger than its elevation above the surface of the surrounding skin. This area is usually formed by many papules enlarging or coalescing to form a total area of greater than 2 cm in diameter. The shape of an area of skin plaque is not necessarily circular, it can take any shape.
Plaque is included in this section because it is a type of skin lesion.