To mend the damage, the body has to lay down new collagen fibres (a naturally occurring protein which is produced by the body).

This process results in a fortuna scar. Because the body cannot re-build the tissue exactly as it was, the new scar tissue will have a different texture and quality than the surrounding normal tissue. An injury does not become a scar until the wound has completely healed.

Most skin scars are of the flat and pale variety, which leave a trace of the original injury which caused them.

Two types of scars are the result of the body overproducing collagen, which causes the scar to be raised above the surrounding skin. Hypertrophic scars take the form of a red raised lump on the skin, but do not grow beyond the boundaries of the original wound, and they often improve in appearance after a few years. Keloid scars are a more serious form of scarring, because they can carry on growing indefinitely into a large, tumorous (although benign) growth.

Both hypertrophic and keloid scars are more common on younger and darker skinned people. They can occur on anyone, but some people have a genetic susceptibility to these types of scarring. They can be caused by surgery, an accident, or sometimes by acne. In some people, keloid scars form spontaneously.

Although they can be a cosmetic problem, keloid scars are only inert masses of collagen and therefore completely harmless, painless, and non-contagious. They tend to be most common on the shoulders and chest. Keloid scars are most common among Asians and Blacks.

Alternately, a scar can take the form of a sunken recess in the skin, which has a pitted appearance. These are caused when underlying structures supporting the skin, such as fat or muscle, are lost. This type of scarring is commonly associated with acne, but can be caused by chickenpox, surgery or an accident.

Scars can also take the form of stretched skin. These are caused when the skin is stretched rapidly (for instance during pregnancy, or adolescent growth spurts), or when skin is put under tension during the healing process, (usually near joints). This type of scar usually improves in appearance after a few years.

Transforming Growth Factors (TGF) play a critical role in scar development and current research is investigating the manipulation of these TGFs for drug development to prevent scarring from the emergency (and rather inappropriate) adult wound healing process.

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