Unfortunately, scars are a fact of life. Their main purpose is to reconstruct skin that has been injured. At first, they may be red or dark and rose after the injury has been healed but will become paler and flatter naturally over time, resulting in a flat, pale scar.

For reasons that are yet to be fully understood, some people form raised scars that are red and thick and may be itchy or painful. Others develop scars that grow beyond the site of a wound, known as keloid scars.

Keloid scars are basically thick, itchy, puckered scars that grow beyond the limits of a wound or incision and rarely regress. They occur when the body keeps producing tough, fibrous protein (called collagen) after a wound has healed.

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

Keloids are fibrotic tumors characterized by a collection of aberrant fibroblasts with high accumulation of extracellular matrix components, mainly fibronectin, elastin, collagen, and proteoglycans. Histologically, keloids contain relatively acellular centers and thick, abundant collagen accumulations that create nodules in the deep dermal section of the lesion. Keloids present a clinical problem that must be addressed as these lesions can cause significant pain, pruritus (itch) and physical disfigurement, may not improve in appearance over time, and can even restrict mobility if located over a joint.

Unlike keloids, hypertropic scars are confined to the wounded site and usally flatten out over time. Hypertrophic scars can be hard to differentiate from keloid scarring microscopically 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 exhibit declining collagen synthesis after about six months. Hypertrophic scars contain 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 condition in the future and must speak with their doctor or surgeon if they are likely to require injections or to have any kind of surgery.

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