Unfortunately, scars are a fact of life. Their main goal is to reconnect skin that has been damaged. Initially, they may be red or dark and rose after the wound has been cured but will become paler and flatter naturally over time, resulting in a flat, pale scar.

For reasons that are still not fully understood, some people form raised scars that are red and thick and may be itchy or painful. Others form scars that grow beyond the site of a wound, called keloid scars.

Keloid scars are actually engrossed, itchy, puckered scars that grow beyond the edges of a wound or incision and rarely regress. They appear when the body keeps producing tough, fibrous protein (known as collagen) after a wound has healed.

Keloid scars can result from any kind of damage to the skin, including scratches, tattoos, insect bites, injections or medical procedures, etc. Keloid scars can appear anywhere on the body, but most usually appear over the breastbone, on earlobes and on shoulders.

Keloids are fibrotic tumors characterized by a collection of atypical fibroblasts with high deposition of extracellular matrix components, mainly fibronectin, elastin, collagen, and proteoglycans. Histologically, keloids have relatively acellular centers and engrossed, abundant collagen bundles that create nodules in the deep skin section of the lesion. Keloids present a clinical challenge that must be attended as these lesions can produce significant pain, pruritus (itch) and physical disfigurement, may not improve in appearance over time, and can even limit mobility if located over a joint.

Unlike keloids, hypertropic scars are limited to the injured site and usally flatten out over time. Hypertrophic scars can be hard to distinguish from keloid scarring histologically and biochemically because both kinds accumulate larger quantities of collagen than normal scars. Both can be caused|the result of surgery, accidents and even acne.

Hypertrophic scars, however, will usually show declining collagen production after about six months. Hypertrophic scars have about twice as much glycosaminoglycans as normal scars, and this and enhanced synthetic and enzymatic reactions result in significant changes in the matrix which alters the mechanical properties of the scars, including decreased extensibility that makes them feel firm.

As with hypertrophic scarring, people having one keloid scar are likely to be prone to this scars in the future and should speak with their doctor or specialist if they are likely to need injections or to have any kind of surgery.

Atrophic scars are characterized by a thinning and reduced elasticity of the skin due to a loss of normal skin architecture. An example of an atrophic scar is striae distensae, also known as stretch marks. This type of scar can also be produced by acne lesions.