How Does Scarring Occur?

Why Scars Form

All mammals have sophisticated self-healing capabilities. Scarring is a by-product of these lifesaving properties. When the skin of a mammal is injured through cuts, scratches, puncture wounds or burns, the body's natural healing processes kick in. Wounds of this kind require skin tissue to basically be rebuilt from scratch. Unless the wound is very superficial, at least part of this rebuilt tissue will be scar tissue. Unfortunately, scar tissue lacks many of the beneficial properties of original dermal tissue, including the abilities to sweat and grow hair.

How Collagen Forms a Scar

When an injury reaches deeper than the superficial layer of skin and damages the thick protective layer called the dermis, scarring occurs. This is a gradual process, beginning with the body increasing its production of the protein collagen. The new collagen cells are used to fill in the gaps created by the wound, and patches of collagen bound together form scar tissue. Usually, the scar tissue is not recognizable as such until the entire wound has completed healing.

Different Types of Scarring

Collagen is light in color, so most scars appear to be lighter than the surrounding skin. And because the body's natural healing process is designed to simply replace the damaged tissue, most scars are relatively even with their surrounding skin.

Sometimes, however, the body produces too much collagen and the scars appear raised and more visible. These scars, called hypotrophic scars, are more likely to form on the injured tissue of very young people. Adults with darker skin are also more prone to hypotrophic scarring than those with lighter skin.

Other scars, called atrophic scars, have a sunken appearance. These scars usually form when the injury was significant enough to damage the tissue layers beneath the dermis, such as the muscle layer. Since the deeper layers support the dermis, what might have otherwise been a flat scar can appear more like a pale-colored gouge. Surgical scars and sometimes acne scars can be atrophic.