Causes of Keloid Scars

Which body parts are most vulnerable?

Keloid scar on wrist

Michael Rodger  / Wikimedia Commons /CC BY 3.0

Keloid scars are defined as abnormal scars that grow beyond the boundary of the original site of a skin injury. The scar is a raised and ill-defined growth of skin in the area of damaged skin, and can cause pain, itching, and burning.

Who and What Is at Risk?

Although a keloid scar can form on anyone, some ethnic groups are at a greater risk of developing them. People with darker skin, such as African Americans, Asians, and Hispanics are more susceptible. Keloid scars are seen 15 times more frequently in highly-pigmented ethnic groups than in Caucasians.

Some areas of the body do seem more susceptible to keloid scars, including the deltoid region of the upper arm, the upper back, and the sternum. The earlobes and the back of the neck are also common sites.

Causes 

It is not fully understood why or how keloid scars form. Skin trauma appears to be the most common cause, although scars can also form for no apparent reason. Skin or muscle tension seems to contribute to keloid formation, as is evidenced by the most common sites of their formation (the upper arm and back). But if that was the full story, you would expect that other sites, such as the palm of the hand or the soles of the feet, to be just as vulnerable; however, this is not the case.

Infection at a wound site, repeated trauma to the same area, skin tension or a foreign body in a wound can also be factors. There does appear to be a genetic component to keloid scarring: it is known that if someone in your family has keloids, then you are at increased risk.

Other theories for the causes of keloid scarring include a deficiency or an excess in melanocyte stiumlating hormone (MSH); decreased percentages of mature collagen and increased soluble collagen; or the blocking of very small blood vessels and the resulting lack of oxygen.

While the lack of a clearcut theory does demonstrate the lack of understanding of the condition, some work is being done to find the cause. Determining the exact cause will hopefully mean better preventative medicine and more effective treatments in the future, but there are many problems with adequate follow up of people with the condition, lack of a clear cut-off from treatment, and too few studies in general — all hampering the search for a cure.

What Can Prevent Keloid Scars?

The fact is that there may be little you can do if you are unfortunate enough to have the sort of skin that reacts by forming keloid scarring. You can assist the healing process by keeping any wounds clean.

If you know you are susceptible because of previous experience or a family connection, then you can avoid taking extra risks. Do not get piercings or tattoos, and make sure you tell your doctor if you are going to have surgery. Some doctors say that all highly pigmented people should avoid tattoos and piercings to be on the safe side.

There is a high rate of recurrence of keloids, up to 50%.

Treatment 

Surgical Treatment

Surgical removal of keloid scars has a very high regrowth rate, anywhere from 50 to 100 percent. Lasers have been tried as an alternative to knife surgery but so far the outcomes are no better.

After scar excision, a silicon gel or sheeting should be applied immediately to the excision site and used daily for six to nine months. (It is clear and makeup can be applied over it.)

If the keloid seems to be reappearing after surgery, injections of a steroid such as triamcinolone can be injected into the lesion to keep recurrence at bay.The injections are given every four to six weeks as needed.

Non-Surgical Treatments

Interferon therapy (drugs acting on the immune system) has been reported as effective in reducing keloid scarring; however, it can have some significant side effects. Examples are toxicity, flu-like symptoms, depression, nausea, and vomiting.

Prolonged compression of scar tissue can theoretically soften and break up keloid scars, but the practicality of this option depends on the location of the keloid. Other non-surgical interventions that are currently being tried with varying results include antihistamines, vitamins, nitrogen mustard, Verapamil, and retinoic acids.

Combined Treatments

Because surgery alone is not very effective, doctors can remove the scar and then provide steroid injections, one at the time of the surgery and the second injection about a month later. However, this type of treatment is variously reported as having between a 50 to 70% rate of recurrence.

Another option combines surgery with external type radiotherapy. Radiation has the effect of interfering with skin growth (fibroblasts) and collagen production. Research varies on which type of combination therapy is more effective.

Both radiotherapy and steroid drugs have side effects, so you need to discuss with your doctor the most effective treatment. It may be worth getting a second opinion before proceeding with either treatment.

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Article Sources

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