What is the pathophysiology of keloids and hypertrophic scars?

Updated: May 29, 2020
  • Author: Brian Berman, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Hypertrophic scars and keloids can be described as variations of typical wound healing. In a typical wound, anabolic and catabolic processes achieve equilibrium approximately 6-8 weeks after the original injury. At this stage, the strength of the wound is approximately 30-40% that of healthy skin. As the scar matures, the tensile strength of the scar improves as a result of progressive cross-linking of collagen fibers. At this point, the scar is usually hyperemic and it may be thickened, but it tends to subside gradually over months until a flat, white, pliable, possibly stretched, mature scar has developed. When an imbalance occurs between the anabolic and catabolic phases of the healing process, more collagen is produced than is degraded, and the scar grows in all directions. The scar is elevated above the skin and remains hyperemic. Excessive fibrous tissue is classified as either a keloid or a hypertrophic scar.

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