Atopic dermatitis

Atopic dermatitis (also known as atopic eczema) is a disorder characterized by inflammation of the skin (dermatitis). The condition usually begins in early infancy, and it often disappears before adolescence. However, in some affected individuals the condition continues into adulthood; in others, it does not begin until adulthood. Hallmarks of atopic dermatitis include dry, itchy skin and red rashes that come and go. The rashes can occur on any part of the body, although the pattern tends to be different at different ages. In affected infants, the rashes commonly occur on the face, scalp, hands, and feet. In children, the rashes are usually found in the bend of the elbows and knees and on the front of the neck. In adolescents and adults, the rashes typically occur on the wrists, ankles, and eyelids in addition to the bend of the elbows and knees. Scratching the itchy skin can lead to oozing and crusting of the rashes and thickening and hardening (lichenification) of the skin. The itchiness can be so severe as to disturb sleep and impair a person's quality of life.

The word "atopic" indicates an association with allergies. While atopic dermatitis is not always due to an allergic reaction, it is commonly associated with other allergic disorders: up to 60 percent of people with atopic dermatitis develop asthma or hay fever (allergic rhinitis) later in life, and up to 30 percent have food allergies. Atopic dermatitis is often the beginning of a series of allergic disorders, referred to as the "atopic march." Development of these disorders typically follows a pattern, beginning with atopic dermatitis, followed by food allergies, then hay fever, and finally asthma. However, not all individuals with atopic dermatitis will progress through the atopic march, and not all individuals with one allergic disease will develop others.

Individuals with atopic dermatitis have an increased risk of developing other conditions related to inflammation, such as inflammatory bowel disease, rheumatoid arthritis, and hair loss caused by a malfunctioning immune reaction (alopecia areata). They also have an increased risk of having a behavioral or psychiatric disorder, such as attention-deficit/hyperactivity disorder (ADHD) or depression.

In a particular subset of individuals with atopic dermatitis, the immune system is unable to protect the body from foreign invaders such as bacteria and fungi (which is known as immunodeficiency). These individuals are prone to recurrent infections. Most also have other allergic disorders, such as asthma, hay fever, and food allergies.

Atopic dermatitis can also be a feature of separate disorders that have a number of signs and symptoms, which can include skin abnormalities and immunodeficiency. Some such disorders are Netherton syndrome; immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome; and severe dermatitis, multiple allergies, metabolic wasting (SAM) syndrome.