A keloid scar is one in which there is overgrowth of dense fibrous tissue. This usually develops after the injury has healed. It extends beyond the borders of the original wound. It does not normally regress spontaneously and it will usually recur after excision. This contrasts with hypertrophic scars, which stay within the borders of the original wound.
This is a companion discussion topic for the original article at https://patient.info/doctor/keloid-pro