Keloid and hypertrophic scars represent an excessive tissue response to dermal injury characterized by local fibroblast proliferation and overproduction of collagen. Keloids are fibrous growth that extend beyond the original area of injury to involve the adjacent normal skin. Hypertrophic scars may have a similar clinical appearance, but in contrast with keloids, remain confined within the boundaries of the wound area and tend to regress spontaneously over time.

Keloids and hypertrophic scars may cause functional impairment and cosmetic disfigurement and are often associated with low self-reported patient quality of life.