Scars are made during the wound-healing process. Normally, cells in damaged skin remove dead cells and debris. The damaged skin then forms a temporary protective structure, composed of randomly placed connective tissue (collagen). Eventually, this temporary structure is replaced by a more orderly and permanent arrangement of tissue.

Initially, a typical scar may be red, sensitive, or itchy as the skin heals. Over time the scar flattens, and its color approaches that of the surrounding skin. A scar never disappears, although it may become less noticeable.

Abnormal scars occur when the temporary connective tissue is not replaced correctly. In hypertrophic and keloid scars, too much temporary connective tissue is made and the skin cannot turn off the process. A hypertrophic scar is raised, red, and often itchy because of the overproduction of connective tissue. Hypertrophic scars are limited to the area of injury. They may be caused by too much tension or stress on a scar, by a wound infection, or by a delay in healing. Some hypertrophic scars resolve after several months of healing; others become cosmetically disfiguring and limit movement. Hypertrophic scars can be linear and associated with a wound or surgical site. Alternatively, hypertrophic scars can be widespread, such as those that follow second- and third-degree burns.

Treatment of hypertrophic scars can include surgical excision, corticosteroid therapy, silicone gel sheeting and pressure therapy. Other treatments under study include radiotherapy, laser therapy, and chemotherapy. [Mustoe et al., 2002]

To date, the best strategy is to prevent hypertrophic scars from occurring by supporting wounds well while they heal and by applying silicone gel sheeting after the wound closes. Corticosteriod treatment also may be required.[Mustoe et al., 2002]

Keloid scars are described as raised, thick, scars that extend beyond the original injury site. Large amounts of scar tissue can be formed from the abnormally high production of connective tissue. These scars can be red and itchy and develop months or even years after the initial skin trauma. Keloids are most common in individuals with dark skin pigmentation, but the underlying genetic factors have not yet been identified. Keloid scars rarely disappear and more than 45% reappear even after their surgical removal.

Keloid scars are easier to prevent than to treat. Based on international clinical recommendations, keloid scars may be prevented by corticosteroid therapy, silicone gel sheeting, pressure therapy, and combinations of these treatments. Some existing keloid scars may be reduced by cryotherapy, and laser therapy shows promise. Existing keloid scars may be removed surgically if they are small, carefully managed postoperatively, and associated with a low risk of recurrence.[Mustoe et al., 2002]