Keloids are an overgrowth of scar tissue at the site of a healed skin injury. Keloids are firm, rubbery lesions or shiny, fibrous nodules and can vary from pink to flesh-colored or red to dark brown in color. They are fairly common in young women and African Americans. Keloids often run in families. Keloidosis is a term used when multiple or repeated keloids occur. A keloid scar is benign, non-contagious and usually accompanied by severe itchiness, sharp pains and changes in texture. 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. Keloids can sometimes be sensitive to chlorine.

Exposure to the sun during the first year of the keloid's formation will cause the keloid to tan darker than surrounding skin. Changes in the cellular signals that control growth and proliferation may be related to the process of keloid formation. Keloids are mostly found on earlobes, the sternum, shoulders, the upper back and any place where abrasion has occurred. These are usually the result of pimples, insect bites, scratching, burns or any other skin trauma. Certain procedures are known to cause keloid formation such as within post-operative surgical scars or on earlobes following piercing and behind the ears after otoplasty. It is estimated that keloids occur in about 10% of people. Darkly pigmented people seem to be more prone to forming keloids. Men and women are equally affected.

Keloids may be often be prevented by using a pressure dressing, silicone gel pad or paper tape over the injury site. Surgery requires great care during and after the operation. Keloids that return after being excised may be larger than the original. The best initial treatment is to inject long-acting cortisone (steroid) into the keloid once a month. Steroid injections are best used as the scar begins to thicken or if the person is a known keloid former. A series of injections with triamcinolone acetonide or another corticosteroid may reduce keloid size and irritation. Laser therapy is an alternative to conventional surgery for keloid removal. Lasers produce a superficial peel but often do not reduce the bulk of the keloid. The use of dye-tuned lasers has not shown better results than that of cold lasers.

Electron beam radiation can be used, which will not go deep enough to affect internal organs. Orthovoltage radiation is more penetrating and slightly more effective. Moistened wound coverings made of silicone gel (such as Dermatix) or silastic have been shown in studies to reduce keloid prominence over time. This treatment is safe and painless. Discoloration from sun exposure can be prevented by covering the forming keloid with a patch or Band-Aid, and by using sunblockers when spending time in the sun. Do not pick at or scratch acne lesions, insect bites, and other skin irritations, and do not pierce your body. Avoid making incisions along the mid-sternal line, and ensure that incisions follow skin creases whenever possible and Langers lines.