A scar can develop after the skin recovers from a skin damage such as surgery, accident or skin disease. Damage to the skin and connective tissue can cause an increase or decrease in tissue. Age, hereditary factors, localization and skin color affect scar formation. An additional wound infection can also cause a scar to heal abnormally.
With these types of scars, too little connective tissue is produced during the healing process. Atrophic scars are often lighter to white in color and somewhat sunken in the skin. Stretch marks are an example of an atrophic scar.
Damage in the connective tissue can cause tissue growth, because too much collagen is produced. Hypertrophic or keloid scars can then develop. Hypertrophic scars are raised and are above the tissue level on the skin. Due to an increased blood supply, these scars are red in color. The scar feels hard and can hurt or itch.
These types of scars usually develop in places where there is a lot of pulling force on the skin, such as on the breastbone, shoulders, knees or elbows.
A keloid scar resembles a hypertrophic scar, however, a keloid scar grows beyond the wound edges. The scars are often abnormally thickened and irregularly shaped. Often these scars occur in young people with dark skin.