Keloid is a scar that appears usually at the site of skin damaged by acne, burns, cuts, chicken pox, insect bites, piercing or tattoo. It surfaces like a hypertrophic scar, but expands outside the wound margins and generally builds over time as the skin heals from its damage. Keloids are benign (non-cancerous) and fibrous skin tumours.

The cells in the skin may produce excessive amounts of collagen with keloid scars and the collagen fibres are also thick and wavy. This makes the appearance of keloids thick and raised causing psychological distress to the victim. Bigger scars may interfere with daily activities and in some rare a keloid may become cancerous. Keloids are more common in people with darker skin and they may appear because of genetic skin disorders or presence of high number of fibroblasts in the skin.