Hypertrophic scars are thickened, raised scars that stay within the boundary of a healing wound. They are usually pink or red, no more than four millimeters above the skin, and can be located anywhere on the body. Keloid scars on the other hand, are thick, raised (over four millimeters above the skin) and are larger than the original wound area. They can be soft or firm, are shiny, lumpy, and hairless, are reddish-brown to purplish in color, and mostly occur on the shoulders, cheeks, earlobes, or chest. Both types of scarring can be painful and itchy, but are otherwise harmless, noncancerous, noncontagious, and are mostly a cosmetic issue that can cause embarrassment or social anxiety. They are more likely to occur in those with darker skin coloring, are between the ages of twenty and thirty, and have a family history of this kind of abnormal

Cells called myofibroblasts produce the protein collagen to aide in the healing of a skin wound. It is believed that hypertrophic and keloid scars occur due to an overproduction of collagen in response to the injury. They may form after any type of skin trauma, including an insect bite, piercing, burn, acne, needle puncture, or minor scratch.

Both forms of scarring have similar treatment options, but keloids are best treated early in their development to minimize growth, and hypertrophic scars are likely to respond better after being allowed to go through the natural healing process for a period of time. Treatment could consist of the use of corticosteroid creams, compression dressings (specifically in newer keloids), cortisone or other steroid injections to flatten the scar, cryotherapy (freezing the area with liquid nitrogen), laser treatment, surgical removal, or a combination of these. Unfortunately, keloids have a high recurrence rate, even after successful treatment.