Health Articles | June 9, 2007 Acne is� most common skin conditions . It is also called common acne. Acne afflicting 40 to 50 million Americans.� Nearly 80 percent of people aged 11 to 30 years have acne, most often on the face, chest and back. However, acne is not restricted to any age group; adults in their 20s, 30s and even into their 40s can get acne. "Old-looking" skin can sometimes have less to do with aging than with a defect that makes the skin look prematurely old.� One such skin problem�and a fairly common one�is acne scars.� Healed acne does leave scars in some people, however, and it is not easy to predict who will have scars after acne and who will not. Most cases of acne responds to treatment and clears up without leaving scars.Severe, inflamed, cystic acne always leaves scars after healing, but in some people even superficially inflamed acne can result in scarring. it can leave a red or hyperpigmented mark on the Skin.White blood cells and inflammatory molecule...