Atopic dermatitis, also referred to as eczema, is an itchy eruption of the skin. It's a long-lasting (chronic) condition that may be accompanied by asthma or hay fever. Atopic dermatitis is most often seen in infants and children, but it can continue into adulthood or first appear later in life.
Although atopic dermatitis may affect virtually any area, it classically involves skin on the arms and behind the knees. It tends to flare periodically and then subside for a time, even up to several years. The exact cause of atopic dermatitis is unknown, but it may result from a malfunction in the body's immune system.