Keloids

• is an overgrowth of tissue at the site of a healed skin injury
• consisting mainly type I and some type III collagen
• form within scar tissue
• benign, non-contagious

characterized by a

• collection of atypical fibroblasts with excessive deposition of extracellular matrix components
• especially collagen
  

1. type I collagen - the most abundant collagen of the human body. It is present in scar tissue, the end product when tissue heals by repair. It is found in tendons, skin, artery walls, the endomysium of myofibrils, fibrocartilage, and the organic part of bones and teeth.
2. type III collagen - the collagen of granulation tissue, and is produced quickly by young fibroblasts before the tougher type I collagen is synthesized