about 20% of people at some point in their lives. It is more common in younger children. Females are affected slightly more often than males. Millions of people have outgrown the condition.

While the condition may occur at any age, it typically begins in childhood, with varying severity over the years. In children under one year of age, the face and limbs and much of the body may be affected. As children get older, the areas on the insides of the knees and folds of the elbows and around the neck are most commonly affected. In adults,