Scar

Scar
Classification and external resources
A minor scar from a cut to the forearm, approx. one year since the wound.
ICD-10	L90.5
MeSH	D002921

Tissues can either regenerate or scar. Scars (also called cicatrices) are areas of fibrous tissue (fibrosis) that replace normal skin (or other tissue) after injury or disease. 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. An exception to this is animals with regeneration, which do not form scars and the tissue will grow back exactly as before.

Scar tissue is composed of the same protein (collagen) as the tissue that it replaces,^[1] but instead of a random basketweave formation of the collagen fibers found in normal tissue,^[1] the collagen cross-links and forms a pronounced alignment in a single direction.^[1] This collagen scar tissue alignment is usually of inferior functional quality to the normal collagen randomised alignment. 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 schara, meaning place of fire (fireplace).^[2]

How scarring occurs

Hypertrophic scarring one year after Road rash on the left, and the original wound on the right.

A scar is a natural part of the body's evolved reaction to injury and is correlated with healing.

Any injury does not become a scar until the wound has completely healed; this can take many months. On the site of the injury the wounded body tissue, in order to repair or patch the defect, over expresses collagen. The collagen over expression cross-links the fiber arrangement inside the collagen. This dense packed collagen, morphing into a inelastic whitish collagen^[3] scar wall, blocks off regeneration, and as a result, the new tissue generated, will have a different texture and quality than the surrounding non wounded tissue. This prolonged collagen producing process results in a fortuna scar.

The scarring is created by fibroblast proliferation,^[3] which reacts to the clot.^[4]

To mend the damage, scars are slowly formed. The scars are formed by prolonged inflammation, excessive over proliferation of fibroblasts^[3] (the proliferation is circular^[5]) and collagen production. Cyclically the fibroblast proliferation lays down thick whitish collagen^[3] inside the matrix, resulting in the abundant production of collagen on the fibers^[4][6][3] giving scars their uneven texture. Over time the fibroblasts continue to crawl around the matrix, adjusting more fibers, in the process the forming scarring becomes more stiff.^[7] This fibroblast proliferation also contracts the tissue.^[8][5] In non wounded tissue these fibers are not over expressed with thick collagen and do not contract.

Redness that often follows an injury to the skin is not a scar, and is generally not permanent (see wound healing). The time it takes for this redness to dissipate may, however, range from a few days to, in some serious and rare cases, a few years.

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

The worse the initial damage is, the worse the scar will generally be.

Skin Scars: Skin scars occur when the dermis (the deep, thick layer of skin) is damaged. And most skin scars are flat and leave a trace of the original injury that caused them.

Stable forms of topical vitamin C have been shown to improve collagen formation^[9].

Recent research has also implicated the gene product osteopontin in scarring and The University of Bristol have developed a gel that inhibits the process^[10][11].

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.^[12]

Scar types

Scar types include hypertrophic scars (of which keloid scars be considered a subset)^[13] which experience excessive growth, recessed scars, and stretch marks (striae).

Hypertrophic

Hypertrophic scars occur when the body overproduces 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. Keloid scars are a more serious form of scarring, because they can carry on growing indefinitely into a large, tumorous (although benign) neoplasm.^[13]

Hypertrophic scars are often distinguished from keloid scars by their lack of growth outside the original wound area, but this commonly taught distinction can lead to confusion.^[13] All keloid scars are hypertrophic^[13] but "only a small percentage of large scars" are keloid.^[13] Phenotypic differences exist between keloid scars and hypertrophic scars.^[13] Keloid scars can occur on anyone, but they are most common in dark-skinned people.^[14] 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-cancerous. However, they can be itchy or painful in some individuals. They tend to be most common on the shoulders and chest.

Other

An atrophic scar takes 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 associated with acne, chickenpox, other diseases, surgery or accidents.

Stretched skin or stretch marks (technically called striae) are also a form of scarring. These 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

According to the authority, the American Academy of Dermatology, no scar can be completely removed^[15] although in some cases healing can occur without scarring such as healing in embryos, healing without injury (regeneration), and some animals. It also depends on race. Eurasians or asians can have it completely removed and some Africans can.^[16] As of 2004^[update] no prescription drugs for the treatment or prevention of scars were available.^[17]

Atrophic Scarring occurring after surgical procedures or trauma is a common cosmetic problem for patients. Atrophic scars, which present as topographical depressions, result when dermal collagen and connective tissue production during the physiologic wound-healing process inadequately compensate for the tissue loss present after injury. Wound tension, tissue apposition, individual variations in wound healing, and scar contraction are all factors that contribute to the creation of a depressed, atrophic scar. With varying success, numerous ablative, nonablative, and fractional devices have been used to stimulate neocollagenesis and dermal remodeling in an attempt to improve the appearance of atrophic scars.^[18]

An alternative way to remove scars is to dissolve them with enzymes. According to Singh, Ratner etal and Lee, Bee Venom Therapy (BVT) is useful in diminishing scars. They explain when scars are stung they are broken down, softened and faded by substances in the venom.^[19][20][21] (Bee sting image: Before and After).^[22]

Semiocclusive ointments (e.g. petrolatum-based), silicone gel sheeting and steroid injections have a widely-accepted role in general scar treatment,^[23]. In 1962, a paper supporting the use of a semiocclusive ointments to speed healing and reduce scarring was published, beginning a practice which is now "a cornerstone of wound care" and the beginning of the discovery of the effectiveness of occlusive methods (ointments, occlusive dressings, silicones) .^[24] The effectiveness of silicone gel over nonsilicone gel was initailly seen as controversial as no significant differences were noted when comparing silicone vs non silicone dressings.^[24] It is now more accepted that the silicone itself is not a biologically active part of scar formation, it is the hydration silicone (and other occlusive dressings) offer. In 2002, Mustoe et al in Vol 110. No 2 of Plastic and Reconstructive Surgery offer the International Recommendations on Scar Management and state, a "primary role for silicone gel sheeting and (corticosteroid injections) for the management of a wide variety of abnormal scars". Corticosteroid therapy by injection into the scars was also introduced in the 1960s. From the early 1970s pressure garment therapy was introduced for widespread burn scars, and silicone gel sheets from the 1980s.^[25]

In 1971 Moss & Clifford, produced a patent that claimed scar free healing.^[26] Their work went unnoticed and was not peer reviewed.

Needling

Needling, also called subcision, dermarolling, or percutaneous collagen induction therapy, began in 1997. It is a process where the scarred area is continuously needled to promote collagen formation. In 2008 a retrospective analysis of 480 persons concluded that it was effective; the patients applied vitamin A and vitamin C to the skin prior to and following the needling.^[27] A 2009 review of the therapy similarly concluded that it was effective.^[28]

The needles are typically standard medical grade stainless steel or newer variants made from titanium which can have minimal diameter yet retain strength and sharpness for reducing pain. The needles are fixed onto a plastic barrel which rotates around an axle that connects to a handle for holding the device. Once needled the area is allowed to fully heal, and needled again if required depending on the intensity of the scar. Scarring needles and needling rollers are available for home use; however, needling should not be done on parts of the face or areas where major nerves are located without professional medical supervision. Needling at home must also be done in line with hygienic and sterilization requirements. Despite the small length of home use needles, it is prudent to ensure that the microneedle roller has been gamma sterilised by the manufacturer as usually these devices are assembled by hand.

It is worth noting that severe scarring is unlikely to benefit from home based treatments as the user is unlikely to be able to penetrate deeply enough to create significant improvements.^[29] In the cases of deep scarring, only professional treatments are likely to work.

Pressure dressing

Pressure dressings are commonly used in managing burn and hypertrophic scars, although supporting evidence is lacking.^[24] These involve elastic materials or gauze which apply pressure to the area. For large scars and particularly large burns, pressure garments may be worn. It is believed that they work by applying constant pressure to surface blood vessels and eventually causing scars to flatten and become softer. Retrospective and ultrasonic studies since the 1960s have supported their use, but the only randomized clinical trial found no statistically significant difference in wound healing.^[24] Care providers commonly report improvements, however, and pressure therapy has been effective in treating ear keloids.^[24] The general acceptance of the treatment as effective may prevent it from being further studied in clinical trials.^[24]

Steroids

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. However, it does cause thinning of the scar tissue so it does carry risks when injected into scars caused by operations into ruptured tendons. This treatment is repeated at 4-6 week intervals.

Topical steroids are ineffective.^[30]

Silicone sheeting and gel

Silicone scar treatments improve scar appearance and are often used to prevent and treat hypertrophic scarring. Although clinical studies spanning 20+ years prove it works…the exact mechanism of action is not fully understood . Studies have suggested several modes of action, quite possible a combination of effects including a manipulation of local ionic charges, an increase in the collagenase activity at the site (Collagenases are enzymes that break the peptide bonds in collagen), or a decrease in production of pro-inflammatory substances like TGFβ2. ^[31]

Dermabrasion

Dermabrasion involves the removal of the surface of the skin with specialist equipment or not and usually involves a local anaesthetic.

Collagen injections

Collagen injections can be used to raise sunken scars to the level of surrounding skin. Its effects can be temporary but will run the chance of a permanent flattening, 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.

Several cosmetic lasers have been FDA approved for the treatment of acne scars by using laser resurfacing techniques. Vascular lasers have been proven to greatly reduce the redness of most scars 6–10 weeks after the initial treatment.

Carbon dioxide ablative fractional resurfacing^[32] is a laser treatment that has been used in acne scarring. It has been theorized that removing layers of skin with a carbon dioxide^[32] or Erbium:YAG laser may help flatten scars.

Scarring caused by acne (left), and photo 1 day after scar revision surgery. Area around sutures is still swollen from surgery

Surgery

Surgical excision of hypertrophic or keloid scars is often associated to other methods such as pressotherapy or silicone gel sheeting. Lone excision of keloid scars however shows a high recurrence rate close to 45%. A clinical study is currently ongoing to assess the benefits of a treatment combining surgery and laser-assisted healing in hypertrophic or keloid scars.

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.

• Is Radiation Therapy for Keloids Acceptable? The Risk of Radiation-Induced Carcinogenesis Article

Chemical peels

Chemical peels are chemicals which destroy the epidermis in a controlled manner, leading to exfoliation and removing certain skin conditions including superficial scars. Various chemicals can be used depending upon the "depth" of the peel and caution should be used, particularly for dark-skinned individuals and also including individuals susceptible to keloid formation or those with active infections.^[33]

Over the counter topical remedies

Ointments and semiocclusive dressings including mineral oil, lotions, and petrolatum-based ointments are recommended under guidelines as they promote moist healing. One 1996 trial found healing was improved but physical characteristics were unchanged, while a 2000 trial of a triple-antibiotic ointment found reduced scarring.^[24]

Research shows the use of vitamin E and onion extract (sold under Mederma) as treatments for scars is ineffective.^[24] Vitamin E causes contact dermatitis in up to 33% of users and in some cases it may worsen scar appearance.^[30] Vitamin C and some of its esters also fade the dark pigment associated with some scars.^[9]

Basic research in animals suggests that Spathodea bark extract, Centella asiatica extract, Anogeissus latifolia bark extract, and Channa striata fish extract in combination with cetrimide cream (a constituent in Savlon) may play a role in wound healing and scar treatment.^[24]

Experimental

Renovo, a British company focusing on skin treatments, is planning Phase III trials for its treatment, which is an intradermal injection of Transforming Growth Factor Beta 3 (TGFβ3) intended to reduce scarring. The results of three trials already completed were published in the Lancet along with an editorial commentary.^[34]

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.

See also

• Dermatology
• Plastic surgery
• Radiation
• Scarification
• Self-injury
• Wound healing
• Dueling scars

References

External links

• WebMD.com article
• American Academy of Dermatology: "What is a scar?"
• Ohio State University Medical Center article
• International Scar Meeting in Tokyo 2010 International Scar Meeting