Atopic dermatitis (AD), also known as atopic eczema, is a long-term type of inflammation of the skin (dermatitis). It results in itchy, red, swollen, and cracked skin. Clear fluid may come from the affected areas, which can thicken over time. AD may also simply be called eczema, a term that generally refers to a larger group of skin conditions.
Atopic dermatitis affects about 20% of people at some point in their lives. It is more common in younger children. Females are slightly more affected than males. Many people outgrow the condition.
While the condition may occur at any age, it typically starts in childhood, with changing 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, the hands and feet are commonly affected. Scratching the affected areas worsens the eczema and increases the risk of skin infections. Many people with atopic dermatitis develop hay fever or asthma.
The cause is unknown but believed to involve genetics, immune system dysfunction, environmental exposures, and difficulties with the permeability of the skin. If one identical twin is affected, the other has an 85% chance of having the condition. Those who live in cities and dry climates are more commonly affected. Exposure to certain chemicals or frequent hand washing makes symptoms worse. While emotional stress may make the symptoms worse, it is not a cause. The disorder is not contagious. A diagnosis is typically based on the signs, symptoms and family history.
Treatment involves avoiding things that make the condition worse, enhancing the skin barrier through skin care and treating the underlying skin inflammation. Moisturising creams are used to make the skin less dry and prevent AD flare-ups. Anti-inflammatory corticosteroid creams are used to control flares-ups. Creams based on calcineurin inhibitors (tacrolimus or pimecrolimus) may also be used to control flares if other measures are not effective. Certain antihistamine pills might help with itchiness. Things that commonly make it worse include house dust mite, stress and seasonal factors. Phototherapy may be useful in some people. Antibiotics (either by mouth or topically) are usually not helpful unless there is secondary bacterial infection or the person is unwell. Dietary exclusion does not benefit most people and it is only needed if food allergies are suspected. More severe AD cases may need systemic medicines such as cyclosporin, methotrexate, dupilumab or baricitinib.
Other names of the condition include "infantile eczema", "flexural eczema", "prurigo Besnier", "allergic eczema", and "neurodermatitis".
Signs and symptoms
Symptoms refer to the sensations that people with AD feel, whereas signs refers to a description of the visible changes that result from AD.The main symptom of AD is itching which can be intense. Some people experience burning or soreness or pain.
People with AD often have a generally dry skin that can look greyish in people with darker skin tones of colour. Areas of AD are not well defined, and they are typically inflamed (red in a light coloured skin or purple or dark brown in people with dark skin of colour). Surface changes include:
scaling cracking (fissures) swelling (oedema) scratch marks (excoriation) bumpiness (papulation) oozing of clear fluid thickening of the skin (lichenification) where the AD has been present for a long time.
Eczema often starts on the cheeks and outer limbs and body in infants and frequently settles in the folds of the skin such as behind the knees, folds of the elbows, around the neck, wrists and under the buttock folds as the child grows. Any part of the body can be affected by AD.
AD commonly affects the eyelids, where an extra prominent crease can form under the eyelid due to skin swelling known as Dennie-Morgan infraorbital folds. Cracks can form under the ears which can be painful (infra-auricular fissure).
The inflammation from AD often leaves "footprints" known as postinflammatory pigmentation that can be lighter than the normal skin or darker. These marks are not scars and eventually go back to normal over a period of months providing the underlying AD is treated effectively.
People with AD often have dry and scaly skin that spans the entire body, except perhaps the diaper area, and intensely itchy red, splotchy, raised lesions to form in the bends of the arms or legs, face, and neck.
Causes
The cause of AD is not known, although some evidence indicates genetic, environmental, and immunologic factors.