Acne is one of most common skin conditions in the world, affecting more than 40 million Americans. Nearly 80 percent of people from ages 11 to 30 years old have acne, most often on the face, chest and back.

But acne isn't restricted to any one age group. Adults who are in their 20s, 30s and even into their 40s can get acne.

Most cases of acne do respond to treatment and clear up without leaving any scars. Healed acne leaves scars in some people however, and it isn't easy to predict who will end up with scars after an acne outbreak and who won't.

Severe, inflamed, cystic acne always leaves scars after healing. And in some people even superficially inflamed acne can result in scarring.

Whether acne scarring is deep or superficial, extensive or scattered, the end result can be less than desirable and even disturbing.

Acne scars can give the skin an aging look. Scars may also contribute to a person looking older than their age as the skin loses its elasticity over the years.

A number of treatments are currently available to remove or improve acne scars. The type and depth of the scars influences the choice of treatment.

Here are some basic facts about acne scars:

Facts about the types of acne scars: Acne scars result from increased tissue formation, response to the inflammation of acne and loss of tissue.

Facts about increased tissue formation: Scars caused by increased tissue formation are caused by a build-up of collagen in the skin. These are called hypertrophic and keloid scars.

Keloids usually are found among several family members. There is a genetic predisposition to form keloids after tissue injury. For example, African-Americans often are prone to keloid formation. Some families also tend to more so, form hypertrophic or thickened scars.

Facts about scars resulting from loss of tissue: Acne scars resulting from loss of tissue are more common than scars resulting from increased tissue formation.

There are several types. They are ice-pick scars, depressed fibrotic scars, superficial and deep soft scars, and atrophic macules.

Ice-pick scars get their name from the way they look. They may be superficial or deep, are usually small and have steep sides like an ice-pick wound. They may be hard or soft.

The soft scars are usually more superficial and the hard scars are usually deeper. The bottom of the hard scar under the skin may be wider than the scar at the surface of the skin.

Depressed fibrotic scars are usually large scars that have sharp edges and steep sides. They look very much like deep chicken pox scars.

Superficial and deep soft scars vary in size. They have sloping edges that merge with normal skin.

Atrophic macules are soft, flat scars that often have a bluish or violet color on white skin due to the underlying blood vessels. These macules tend to fade away over time and become less obvious.

Acne scars are an ongoing reminder of a common skin condition that can cause embarrassment and social isolation. Acne scars can also contribute to the appearance of premature aging.

The good news is that today, there are several types of treatments to choose from for acne scar removal,. See your dermatologist or dermatologic surgeon for the best acne scar treatment for you.