Hypertrophic scar

A hypertrophic scar is a cutaneous condition characterized by deposits of excessive amounts of collagen which gives rise to a raised scar, but not to the degree observed with keloids. Like keloids, they form most often at the sites of pimples, body piercings, cuts and burns. They often contain nerves and blood vessels. They generally develop after thermal or traumatic injury that involves the deep layers of the dermis and express high levels of TGF-β.

Cause
Mechanical tension on a wound has been identified as a leading cause for hypertrophic scar formation.

When a normal wound heals, the body produces new collagen fibers at a rate which balances the breakdown of old collagen. Hypertrophic scars are red to brown and thick and may be itchy or painful. They do not extend beyond the boundary of the original wound, but may continue to thicken for up to six months. Hypertrophic scars usually improve over one or two years, but may cause distress due to their appearance or the intensity of the itching; they can also restrict movement if they are located close to a joint.

Some people have an inherited tendency to hypertrophic scarring, for example, those with Ehlers–Danlos syndrome.

Prevention
It is not possible to completely prevent hypertrophic scars, so those with a history of them should inform their doctor or surgeon if they need surgery. For example, pressure garment therapy is a commonly used approach used to try and prevent hypertrophic scarring after a burn, but the effectiveness of this approach is unclear.

Management
Early hypertrophic scars should be treated with applied pressure and massage in the first 1.5–3 months. If necessary, silicone therapy should be applied later. Ongoing hypertrophy may be treated with corticosteroids injections. Surgical revision may be considered after 1 year.

Silicone gel sheeting
Silicone gel sheeting is sometimes used to treat hypertrophic scars. Silicone gel sheets may improve the appearance of scars slightly compared with applying onion extract, and may reduce pain compared with no treatment with silicone gel sheets or pressure garments. It is uncertain whether silicone gel sheets are more effective than other treatment approaches.

Laser therapy
Laser therapy is an approach that has been studied for treating hypertrophic scars. There is not enough evidence to determine if laser therapy is more effective than other treatments or if laser therapy leads to more harm than benefits as compared with no treatment or different kinds of treatment.

Cryosurgery
Cryosurgery, using extreme cold to remove dead tissue, may speed up the healing process from a hypertrophic scar to a flatter, paler one.