What are keloid and hypertrophic scars?
Keloid scars are hard, raised nodules that develop in the skin at the site of an injury as part of the body’s normal healing process. The injury may be accidental, surgical, cosmetic or due to infection such as acne. After an injury, skin cells called fibroblasts begin multiplying to repair the damage. In normal wound healing, the fibroblasts produce only sufficient connective tissue, to mend the wound. In people prone to keloid scarring, the fibroblasts continue to produce connective tissue even after the wound is adequately repaired, creating the overgrowth of dense fibrous tissue known as keloid or hypertrophic scars.
- Keloid scars tend to grow beyond the size of the original injury which means even a small injury such as a pimple can result in a large scar. Keloids are often raised, red, firm nodules that may also be discoloured, painful or itchy. Keloids usually don’t get better with time. They may form on any part of the body, although the upper chest, shoulders, upper back and earlobes are especially prone. Burn scars or infected lesions, including acne, are more likely to form keloids.
- Approximately 10% of people are prone to keloid scarring. Men and women are equally prone, though they are more common in those with darker skin. They form mainly in younger people with the peak age being 10-30 years. They are less common at the extremes of age. There may be a family history of tendency to develop keloids.
- Hypertrophic scars look similar to keloid scarring, but are contained within the boundary of the initial injury. Hypertrophic scarring is more common than keloid scarring and is also more likely to gradually improve over time. It is less likely to be painful or itchy. Hypertrophic scars usually appear within a month of the injury, grow for several months and then regress; whereas, keloid scars may appear later and continue growing for longer.
Treatment of keloid scars:
Keloid scars are difficult to treat and combinations of different treatments are often most effective.
- Anti-inflammatory Injections: are the mainstay of treatment and prevention. Injections are given at 3-4 weekly intervals until improvement occurs. Hypertrophic scars often respond completely. Keloids can be more resistant and recurrences can occur. Injections are comfortable and safe, as very little gets into the bloodstream. Risks include too vigorous a response which can transform a raised scar into an indented depressed scar. For this reason, initial treatments must be conservative. Injections can also stimulate the formation of new blood vessels. These can can be treated using a vascular laser. (See below) While injections generally improve the appearance of keloids, even the best result will leave a mark that looks and feels different from the surrounding skin. Cost: $150-$250 per treatment (Medicare rebates apply)
- Laser treatment: Vascular lasers are used to improve colour and to help flatten keloid scars. Fractional laser resurfacing or skin needling are sometimes used to help re-organise collagen fibres in keloid scars and can result in smoothing and flattening. Laser treatments are often combined with a course of cortisone injections.
- Silicone gels and tapes: These are most successful when applied early in the course of keloid or hypertrophic scar formation. Silicone gel or sheeting is worn continuously 24 hours a day for 2-3 months. Silicone gels are thought to work by stimulating new collagen to grow in a more organised way and may help to reduce pain, swelling and itching.
- Surgical removal of keloid scars is best avoided in most instances as cutting a keloid can make scarring worse by stimulating further fibroblast activity and creating even more scar tissue. Some surgeons achieve success by injecting steroids or applying pressure dressings to the wound site after cutting away the keloid.
For people at high risk of with a history of keloids:
- Avoid body piercing, tattoos and unnecessary incisions such as cosmetic surgery – particularly to skin sites more prone to keloid formation.
- Treat acne thoroughly to reduce lesions and potential for scarring.
- If surgery is required, it may be combined with dressings, intralesional steroids or other treatments to reduce the likelihood or size of keloid scarring. Care with surgical technique is important.