A scar results from the biologic process of wound repair in the skin and other tissues of the body. Thus, scarring is a natural part of the healing process. With the exception of very minor lesions, every wound (e.g. after accident, disease, or surgery) results in some degree of scarring.
Scar tissue is not identical to the tissue which it replaces and is usually of inferior functional quality. For example, scars in the skin are less resistant to ultraviolet radiation, and sweat glands and hair follicles do not grow back within scar tissue, myocardial infarction causes scar formation in the heart muscle which leads to loss of muscular power and possibly heart failure. However, there are some tissues (e.g. bone) which can heal without any structural or functional deterioration.
A scar is a natural part of the healing process. Skin scars occur when the deep, thick layer of skin (the dermis) is damaged.
To mend the damage, the body has to lay down new collagen fibres (a naturally occurring protein which is produced by the body).
This process results in a scar. Because the body cannot re-build the tissue exactly as it was, the new scar tissue will have a different texture and quality to the surrounding normal tissue. An injury does not become a scar until the wound has completely healed.
Most skin scars are of the flat and pale variety, which leave a trace of the original injury which caused them.
Sometimes the body can over-produce collagen, which results in a scar which is raised above the surrounding skin, these are known as either Hypertrophic scars or Keloid scars. Hypertrophic scars take the form of a red raised lump on the skin, but do not grow beyond the boundaries of the original wound, and they often improve in appearance after a few years. Keloid scars are a more serious form of scarring, because they can carry on growing indefinitely into a large, tumorous (although benign) growth. These are caused when the body doesn't know when to stop producing collagen.
A person's shoulder displaying keloid scars and acneBoth hypertrophic and keloid scars are more common on younger and darker skinned people. They can occur on anyone, but some people have a genetic succeptibility to these types of scarring. They can be caused by surgery, an accident, or sometimes by acne. In some people, keloid scars form spontaneously.
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