scar

[skahr]

scar, fibrous connective tissue that forms at the site of injury or disease in any tissue of the body. Scar tissue may replace injured skin and underlying muscle, damaged heart muscle, or diseased areas of internal organs such as the liver. Dense and thick, it is usually paler than the surrounding tissue because it is poorly supplied with blood, and although it structurally replaces destroyed tissue, it cannot perform the functions of the missing tissue. Scar tissue may therefore limit the range of muscle movement or prevent proper circulation of fluids when affecting the lymphatic or circulatory system. Extensively scarred tissue may lose its ability to function normally.

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Licensed from Columbia University Press

scar

Mark left on the skin after a wound heals. Cells called fibroblasts produce collagen fibres, which form bundles that make up the bulk of scar tissue. Scars have a blood supply but no oil glands or elastic tissue, so they can be slightly painful or itchy. Hypertrophic scars grow overly thick and fibrous but remain within the original wound site. Scars can also develop into tumourlike growths called keloids, which extend beyond the wound's limits. Both can inhibit movement when they result from serious burns over large areas, especially around a joint. Scars, especially those from unaided healing of third-degree burns, can become malignant. Treatment of serious scars is one of the most important problems in plastic surgery.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

Scar

Scars (also called cicatrices) are areas of fibrous tissue that replace normal skin (or other tissue) after injury. A scar results from the biologic process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound (e.g. after accident, disease, or surgery) results in some degree of scarring.

Scar tissue is not identical to the tissue that it replaces and is usually of inferior functional quality. For example, scars in the skin are less resistant to ultraviolet radiation, and sweat glands and hair follicles do not grow back within scar tissue. A myocardial infarction, commonly known as a heart attack, causes scar formation in the heart muscle, which leads to loss of muscular power and possibly heart failure. However, there are some tissues (e.g. bone) that can heal without any structural or functional deterioration.

The word scar was derived from the Greek word eschara, meaning place of fire (fireplace).

How scarring occurs

A scar is a natural part of the healing process. Skin scars occur when the deep, thick layer of skin (the dermis) is damaged. The worse the damage is, the worse the scar will be.

Most skin scars are flat, pale and leave a trace of the original injury that caused them. The redness that often follows an injury to the skin is not a scar, and is generally not permanent. The time it takes for it to go away may, however, range from a few days to, in some serious and rare cases, a few years. Various treatments can speed up the process in serious cases.

Scars form differently based on the location of the injury on the body and the age of the person who was injured.

To mend the damage, the body has to lay down new collagen fibres (a naturally occurring protein that is produced by the body). Recent research has implicated the gene osteopontin in scarring and developed a gel that inhibits the process .

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.

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 adult wound healing process. As well, a recent American study implicated the protein Ribosomal s6 kinase (RSK) in the formation of scar tissue and found that the introduction of a chemical to counteract RSK could halt the formation of Cirrhosis. This treatment also has the potential to reduce or even prevent altogether other types of scarring.

Abnormal scars

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.

Keloid scars can occur on anyone, but they are most common in dark-skinned people. Keloid scars can be caused by surgery, an accident, by acne or, sometimes, from body piercings. 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 and non-contagious. However, they can be itchy or painful in some individuals. They tend to be most common on the shoulders and chest.

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 called striae and are caused when the skin is stretched rapidly (for instance during pregnancy, significant weight gain 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.

Treatments for skin scars

No scar can ever be completely removed and treatments will always leave a trace, but a number of approaches have been tried with silicon gel sheeting and steroid injections having the most widely accepted role in general scar treatment.

In historical sequence, corticosteroid therapy by injection into the scars was introduced in the 1960s, from the early 1970s pressure garment therapy was introduced for widespread burn scars, and silicone gel sheets from the 1980s.

Topical treatments

Silicone gel and silicone sheets were claimed in multiple published medical studies to help flatten and soften raised scars if applied regularly. However, a review-article published 2006 concludes that "Trials evaluating silicon gel sheeting as a treatment for hypertrophic and keloid scarring are of poor quality and highly susceptible to bias. There is weak evidence of a benefit of silicon gel sheeting as a prevention for abnormal scarring in high risk individuals but the poor quality of research means a great deal of uncertainty prevails." Silicone sheeting is considered a non-invasive Class 1 Medical device, and is easier to use and with lower risks of side effects compared to surgical excision, steroid injections, pressure therapy, laser and cryotherapy treatments.

Pressure garments

Pressure garments should be used only under supervision by a medical professional. They are most often used for burn scars that cover a large area, this treatment is only effective on recent scars.

Pressure garments are usually custom-made from elastic materials, and fit tightly around the scarring. They work best when they are worn 24 hours a day for six to twelve months.

It is believed that they work by applying constant pressure to surface blood vessels and eventually causing scars to flatten and become softer.

Steroid injections

A long term course of steroid injections under medical supervision, into the scar may help flatten and soften the appearance of keloid or hypertrophic scars.

The steroid is injected into the scar itself; since very little is absorbed into the blood stream, side effects of this treatment are minor. This treatment is repeated at 4-6 week intervals.

Dermabrasion

Dermabrasion involves the removal of the surface of the skin with specialist equipment and usually involves a general anaesthetic. It is useful with raised scars, but is less effective when the scar is sunken below the surrounding skin.

Collagen injections

Collagen injections can be used to raise sunken scars to the level of surrounding skin. Its effects are however temporary, and it needs to be regularly repeated. There is also a risk in some people of an allergic reaction.

Laser surgery & resurfacing

The use of lasers on scars is a new form of treatment that is still being improved.

Vascular lasers have been proven to greatly reduce the redness of most scars 6-10 weeks after the initial treatment. They have not been proven effective in flattening scars however. It has been theorized that removing layers of skin with a carbon dioxide or erbium laser may help flatten scars.

Several cosmetic lasers have been FDA approved for the treatment of acne scars by using laser resurfacing techniques.

Surgery

Scars, such as acne scars, can be cut out and stitched up, a process called scar revision - Although this method has been known to result in the new wound to heal the same way (as a hypertrophic scar).

Radiotherapy

Low-dose, superficial radiotherapy, is used to prevent re-occurrence of severe keloid and hypertrophic scarring. It is usually effective, but only used in extreme cases due to the risk of long-term side effects.

Natural remedies

Research shows the use of vitamin E and onion extract as a treatment for scars has been proven ineffective, though in some cases it may worsen scar appearance.

Intentional scarring

The permanence of scarring has led to its intentional use as a form of body art within some cultures and subcultures (see scarification). These forms of ritual and non ritual scarring practices can be found in many groups and cultures around the world.