What Causes Keloid Scarring?

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Keloid scarring occurs after damage to the skin in susceptible individuals. This injury can be minor such as acne, an insect bite or body piercing. Keloid scars behave like benign growths, but unlike other scars, they extend beyond the original injury. Apart from their unsightly appearance a study in 2004 by Lee and colleagues, published in the “Journal of the American Academy of Dermatology,” showed that the majority of patients with a keloid suffered pain and/or itching. Keloids will not regress or improve over time and have a high recurrence rate after surgery.


Keloid scarring is common in individuals from certain ethnic groups with the most affected being African-Americans and the least affected being Caucasians. Most keloid scars are sporadic; however, an article published in the "Archives of Dermatology" in 2001 outlined a study of 14 families that found that some families do show a genetic trait. This trait could be transmitted by either the mother or father with the children having a 50 percent chance of developing a keloid scar. The same study suggested that the variability seen and the different individual responses indicate that keloid scarring must involve more than one gene, yet to be determined.

A study published in 2010 in the “Archives of Dermatological Research” showed that keloid scarring may be related to certain variations of the proteins that stimulate an immune response, called the human leukocyte antigens.

Anatomical Position

Keloid scars appear more common on certain areas on the body and rare on other areas. In a 2004 article published in the “Journal of Plastic Surgery,” researchers reported that keloid scarring was more frequent on the chest, upper back, back of the neck, shoulders and earlobes.

Growth Factors

Growth factors are the chemical messengers that signal to the cells to change their behavior. Many growth factors are involved in both scarring and wound healing. Keloid scarring is associated with the abnormal expression of a number of these growth factors. In a 2006 article published in the “Journal of Investigative Dermatology,” a team of researchers showed that keloid scarring requires more than one abnormally expressed growth factor. Wound healing and scarring involves not only chemical signals but a vast array of different cell types, many cells or their responses have also been shown to be altered in the formation of keloid scars.


Some rare syndromes have an increased incidence of keloid formation. Rubinstein-Taybi and Goeminne are two such syndromes. Individuals with these syndromes, however, not only have an increased frequency of keloid scarring but have other characteristic traits. The genetic abnormalities have already been identified for a number of these syndromes.