Severe burn scars, for example, tend to have a puckered appearance. Acne may leave deep pits in the skin. Some sars, rather than shrinking, grow abnormally, forming hypertrophic scars. Keloids, a type of hypertrophic scar that results from an overproduction of collagen, continue growing beyond the margins of the original wound. Even a small scar may draw unwanted attention if it cuts across the face's natural creases and contours, and any scar that is unusually large, uneven, or differently colored may be nearly impossible to camouflage.
Some scars actually interfere with the normal function of facial features.
A scar that contracts as it heals may restrict the movement of muscles and tendons or pull the lip or eyelid into an unnatural position. Although scars cannot be entirely removed, they can be made less noticeable, and normal function, in most cases, can be restored or at least significantly improved. This means simply removing the scar by cutting it out. It is often used on hypertrophic scars. The goal of excision is to make a smaller, neater scar.