Scars overview

Scars are a result of normal healing process. Generally, scarring occurs when the wound/lesion is significant enough to damage the dermis, the key structural layer of the skin.

The degree of scarring that develops is affected by several factors:

• Size/type/location of the wound/lesion
• Individual physiology, which, in turn, depends on genetics, age, etc.
• Effects of the external environment on the healing process, e.g. wound care/protection, control of infection, avoidance of irritants, etc.
• Use of specific agents that may inhibit or modify scar formation (e.g. silicone gel sheets)

Scar formation involves many events, including deposition of new collagen, migration and division of cells (particularly fibroblasts), changes in blood supply to the affected area and many others. The primary goal of wound healing is to close the wound as quickly as possible in order to prevent infection.

When wounded, the body is more concerned about survival than "looking good". (After all, what's the point of looking good if you develop a deadly infection.) Therefore, the wound repair system goes into overdrive, initially making a quick, crude repair with basic materials (such as type III collagen). As a result, early scars tend to look especially prominent, irregular and sometimes flushed/reddish (due to pronounced growth of capillaries).

After the initial (fresh) scar has been formed, it continues to evolve over the following days, months or even years. Much of the type III collagen in the scar is recycled and replaced by the stronger and more regular type I collagen. The capillaries recede and the scar eventually becomes relatively flat and pale. Yet the scar remains distinct from the surrounding skin; its shape approximately reflecting the area of the original damage.

Scars are often more pale than the surrounding skin because they tend to contain fewer melanocytes (pigment producing cells) than the normal skin. However, in darker skinned people, scars may sometimes have hyper-pigmented areas, especially along the edges.

Abnormal scars

Hypertrophic scars

Hypertrophic scars are raised, firm and often reddish (erythematous) scars that are more unsightly than regular scars. They develop as a result of excessive early phases of the wound healing response that are not followed by proper later remodeling of the scar tissue. In particular, too much collagen (especially type III) is deposited and too many new capillaries are created in the early phases of wound healing. Furthermore, the subsequent recycling of excess collagen and/or suppression of capillary growth does not occur to a sufficient degree. However, hypertrophic scars (as opposed to keloids) stabilize and stay roughly within the boundaries of the area of initial injury.

Keloid scars

Just as hypertrophic scars, keloid scars are characterized by excessive early phases of the wound healing response that are not followed by proper later remodeling of the scar tissue. However, keloids extend beyond the margins of the initial wound and do not regress over time. Predisposition to keloid scars appears to be genetic. Although keloids can be seen in all skin types, they are more common in patients with darker skin tones.

Atrophic scars

Atrophic scars are skin depressions associated with excessive dermal collagen degradation, usually caused by inflammatory lesions, such as acne cyst or varicella. Acne may cause saucerized, ice pick or boxcar scars.

Treatments

While no scar can be completely eliminated, its appearance can often be improved with treatment. A wide variety of methods have been used to treat scars. Treatment is generally tailored to the type of the scar. See Scar Treatment.