Keloid

An excessive deposition of extracellular matrix at the wound site results in a hypertrophic scar or a keloid. The rate of collagen synthesis, the ratio of type III to type I collagen, and the number of reducible cross-links remain high, a situation that indicates a maturation arrest , or block, in the healing process. An excessive formation of collagenous tissue results in the appearance of a raised area of scar tissue called keloid. It is an exuberant scar that tends to progress and recur after excision. The cause of this is unknown. Genetic predisposition, repeated trauma, and irritation caused by foreign body, hair, keratin, etc., may play a part. It is especially frequent after burns. It is common in areas of the neck & in the ear lobes. Keloid, also known as keloid disorder and 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 color of the person s skin or red to dark brown in color. 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 people of African descent than in people of European descent.Keloids should not be confused with hypertrophic scars, which are raised scars that do not grow beyond the boundaries of the original wound.Histologically, keloids are fibrotic tumors characterized by a collection of atypical fibroblasts with excessive deposition of extracellular matrixcomponents, 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.