|Classification and external resources|
Postoperative keloid on the wrist
A keloid (//; also keloidal scar) is the formation of a type of scar which, depending on its maturity, is composed mainly of either type III (early) or type I (late) collagen. It is a result of an overgrowth of granulation tissue (collagen type 3) at the site of a healed skin injury which is then slowly replaced by collagen type 1. Keloids are firm, rubbery lesions or shiny, fibrous nodules, and can vary from pink to the colour of the patient's flesh or red to dark brown in colour. A keloid scar is benign and not contagious, but sometimes accompanied by severe itchiness, pain, and changes in texture. In severe cases, it can affect movement of skin. Keloid scars are seen 15 times more frequently in highly pigmented ethnic groups than in Caucasians.
Keloids should not be confused with hypertrophic scars, which are raised scars that do not grow beyond the boundaries of the original wound.
Signs and symptoms
Keloids expand in claw-like growths over normal skin. They have the capability to hurt with a needle-like pain or to itch without warning, although the degree of sensation varies from person to person.
If the keloid becomes infected, it may ulcerate. Removing the scar is one treatment option; however, it may result in more severe consequences: the probability that the resulting surgery scar will also become a keloid is high, usually greater than 50%. Laser treatment has also been used with varying degrees of success.
Keloids form within scar tissue. Collagen, used in wound repair, tends to overgrow in this area, sometimes producing a lump many times larger than that of the original scar. Although they usually occur at the site of an injury, keloids can also arise spontaneously. They can occur at the site of a piercing and even from something as simple as a pimple or scratch. They can occur as a result of severe acne or chickenpox scarring, infection at a wound site, repeated trauma to an area, excessive skin tension during wound closure or a foreign body in a wound. Keloids can sometimes be sensitive to chlorine. Keloid scars can grow, if they appear at a younger age, because the body is still growing.
Keloids can develop in any place where an abrasion has occurred. They can be the result of pimples, insect bites, scratching, burns, or other skin trauma. Keloid scars can develop after surgery. They are more common in some sites such as the central chest, the back and shoulders and the ear lobes. They can also occur on body piercings. The most common spots are earlobes, arms, pelvic region, and over the collar bone.
Most skin injury types can contribute to keloid scarring. This includes acne scars,burns, chickenpox scars, ear piercing, scratches, surgical cuts or vaccination sites.
According to the National Center for Biotechnology Information, keloid scarring is common in people between the ages of 10 and 20, and also among African Americans, Asians, and Hispanics.
Keloids tend to have a genetic component, which means you are more likely to have keloids if one or both of your parents has them. 
Histologically, keloids are fibrotic tumors characterized by a collection of atypical fibroblasts with excessive deposition of extracellular matrix components, especially collagen, fibronectin, elastin, and proteoglycans. Generally, they contain relatively acellular centers and thick, abundant collagen bundles that form nodules in the deep dermal portion of the lesion. Keloids present a therapeutic challenge that must be addressed, as these lesions can cause significant pain, pruritus (itching), and physical disfigurement. They may not improve in appearance over time and can limit mobility if located over a joint.
Keloids affect both sexes equally, although the incidence in young female patients has been reported to be higher than in young males, probably reflecting the greater frequency of earlobe piercing among women. The frequency of occurrence is 15 times higher in highly pigmented people. African descendant people have increased risk of keloid occurrences.
The best treatment is prevention in patients with a known predisposition. This includes preventing unnecessary trauma or surgery (including ear piercing, elective mole removal), whenever possible. Any skin problems in predisposed individuals (e.g., acne, infections) should be treated as early as possible to minimize areas of inflammation.
Should keloids occur, the most effective treatment is superficial external beam radiotherapy (SRT), which can achieve cure rates of up to 90%.
Persons of any age can develop a keloid. Children under 10 are less likely to develop keloids, even from ear piercing. Keloids may also develop from Pseudofolliculitis barbae; continued shaving when one has razor bumps will cause irritation to the bumps, infection, and over time keloids will form. Persons with razor bumps are advised to stop shaving in order for the skin to repair itself before undertaking any form of hair removal. The tendency to form keloids is speculated to be hereditary. Keloids can tend to appear to grow over time without even piercing the skin, almost acting out a slow tumorous growth; the reason for this is unknown. If a keloid grows too large, removal is the only solution, resulting in a scar or, in worst cases, amputation.
Keloids were described by Egyptian surgeons around 1700 BC. Baron Jean-Louis Alibert (1768–1837) identified the keloid as an entity in 1806. He called them cancroïde, later changing the name to chéloïde to avoid confusion with cancer. The word is derived from the Greek χηλή, chele, meaning "hoof", here in the sense of "crab pincers", and the suffix -oid, meaning "like". For many years, Alibert's clinic at Hôpital Saint-Louis was the world’s center for dermatology.
|Young male with bilateral keloid formation on the plantar surfaces of feet|
- Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. p. 1499. ISBN 1-4160-2999-0.
- Ogawa R (February 2010). "The most current algorithms for the treatment and prevention of hypertrophic scars and keloids". Plast. Reconstr. Surg. 125 (2): 557–68. doi:10.1097/PRS.0b013e3181c82dd5. PMID 20124841.
- Meenakshi J, Jayaraman V, Ramakrishnan KM, Babu M (2005). "Keloids and hypertrophic scars: a review". Indian J Plast Surg 38 (2): 175–9. doi:10.4103/0970-0358.19796.
- Kathleen Collins, "The Scourged Back," History of Photography 9 (January 1985):hy 43-45.
- Wound Healing, Keloids at eMedicine
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