When a scar is engrossed, it does not invade healthy tissue and lies across the relaxed skin tension lines (creases in the skin). This kind of scar is referred to as hypertrophic.

In the case that it is a raised scar and invades healthy tissue, then it is called a keloid scar. All kinds of scarring can occur on different areas of the body, but some areas such as the chest, knees and elbows are more likely to scar.

Both keloid and hypertrophic scar tissues are atypical reactions to damage. However, a keloid is an abnormal scar that grows beyond the boundaries of the original site of skin injury.

Keloids have the clinical appearance of an elevated amorphous growth and are usually associated with pruritus and pain. Microscopy observation shows randomly disposed collagen fibers in a dense connective tissue matrix, making keloid removal a difficult task. In normal scars, the collagen bundles are disposed parallel to the skin surface.

A hypertrophic scar is an engrossed or unsightly scar that does not extend beyond the original boundaries of the wound. Unlike keloids, scars caused by hypertrophic actinic keratosis grow to a certain size and subsequently stabilize or regress. Like keloids, hypertrophic scars are associated with negative wound healing factors.

There are no particular characteristics that can indicate what will be the ultimate appearance of a scar or what kind of scar it will be. The way in which a wound cures is different for every person and is determined by genes, the environment and how you care for it.

Keloid or hypertrophic scar: A review of the literature

Atiyeh BS, Costagliola M, Hayek SN.

Division of Plastic and Reconstructive Surgery, American University of Beirut Medical Center, Beirut, Lebanon.

Keloid and hypertrophic scars are two kinds of exaggerated scarring observed clinically that need different treatment approaches. The clinical course and physical appearance define keloids and hypertrophic scars as different entities; however, they are usually confused because of an apparent lack of morphologic differences. Nevertheless, clinical differences between hypertrophic scars and keloids have long been known by plastic surgeons and specialists. Yet, expressing these differences into morphologic or biochemical signs has created much conflict in the literature. This report is an attempt to clarify the longstanding controversy regarding these 2 similar yet separate and nonidentical entities by explaining the reported points of individualization as well as the similarities.

Quality of life of patients with keloid and hypertrophic scarring.

Bock O, Schmid-Ott G, Malewski P, Mrowietz U.

Primary Health Care Center, Halsan 2, Fabriksgatan 17, 55 185, Jonkoping, Sweden.

Keloid and hypertrophic scarring are chronic disfiguring dermatoses with a high resistance to treatment. The objective of our research was to assess for the first time the quality of life of people with hypertrophic scars and keloids, because they suffer from quality of life deprivation as much as people with other chronic skin ailments. An item-pool was created modifying and supplementing the items of the Questionnaire on Experience with Skin Complaints. The questionnaire was distributed to 100 outpatients with keloids and hypertrophic scars. A factor analysis was used to identify the underlying dimensions. Two scales (psychological and physical deprivation) of the questionnaire with 9 and 5 items, respectively, were used. Test-retest validity of the questionnaire was excellent (corr>0.9). Good validity was proposed by the correlation of physical deprivation with pain (P less or equal to 0.001), pruritus (P less than 0.001), and the amount of impediment of mobility (P less than 0.001). The psychological scale was associated with pain and impediment of mobility, although the relationships were minor. This research shows for the first time a deprivation of quality of life in a large group of sufferers with keloid and hypertrophic scarring.