Medical hypotheses
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Keloids and hypertrophic scars are fibroproliferative disorders (FPDs) of the skin that result from abnormal healing of injured or irritated skin. They can be called pathological or inflammatory scars. Common causes are trauma, burn, surgery, vaccination, skin piercing, folliculitis, acne, and herpes zoster infection. ⋯ Thus, primary scars are caused by congenital endothelial dysfunction (e.g., a mutation prevents endothelial gaps from closing smoothly) while secondary scars are caused by endothelial dysfunction that results from aging, arterial sclerosis, and/or repeated/very strong local mechanical forces. We expect that primary keloids develop at younger ages and tend to become severe, while secondary keloids are seen in all ages and can vary in clinical severity. Thus, abnormal blood vessel regulation may underlie keloid and hypertrophic scar pathogenesis, which suggests that inhibiting abnormal angiogenesis and vascular hyperpermeability may be an important therapeutic approach.