Scars form when the body forms new collagen fibers to heal a wound. The skin damage may have been caused by accidents, previous surgeries, skin conditions, or burns the patient may have experienced in the past.

However, raised scars can form if the body produces more collagen than is necessary to heal the wound. There are two main categories of elevated scars: keloids and hypertrophic scars.

While both keloids and hypertrophic scars result from collagen overproduction, their effects are distinct. The formation of a hypertrophic scar follows a laceration of the skin, while the development of a keloid may take up to a year. Keloids, in contrast to hypertrophic scars, actively spread into neighboring healthy tissue as they form collagen fibers. Surrounding healthy tissue is unharmed.

Atrophic scars, on the other hand, leave a depressed area on the skin and appear wrinkled. Scars form when dermal tissue is lost due to an injury and not adequately replaced by collagen during the healing process. Common skin conditions like acne often leave behind atrophic scars.