Atopic Eczema (Dermatitis)
Eczema is a pattern of itchy skin rash consisting of tiny pink bumps that may join together producing ill-defined pink or red patches. There are many types of eczema – some have known causes. Dermatitis is the term used for eczema reactions that are caused by external agents/factors. Atopic eczema is often referred to as “infantile” or childhood eczema because that is when it usually develops. Atopic eczema is usually associated with allergies (hayfever or asthma) in either the affected individuals or in their close relatives.
Eczema changes with age.
Eczema commonly begins in infancy as dry patches which may be inflamed (pink) and may also be wet/oozy. The affected areas can be very extensive, affecting the face and head, in particular, the body and limbs, but it often spares deep folds (armpits and groin). As the baby starts crawling, eczema usually becomes localised to sites in close (frictional) contact with the environment – fronts of knees, wrists, ankles. When the child starts walking eczema tends to be localised to the fronts of the elbows, backs of the knees, neck and face. Eczema may range in severity from mild and easily controlled to extensive, severe and very difficult to control.
Other types of eczema/dermatitis that can be confused.
Seborrhoeic eczema/dermatitis: A dry, scaly type of eczema that affects babies, causing cradle cap and sometimes weepy eczema of the head, face and in the deep folds – not associated with allergies. Allergic contact dermatitis: An allergic reaction to substances that contact the skin – such as metal (jewellery), scents, dyes and ingredients of creams. This occurs at the sites of contact with the causative agent.
Causation/aggravation of atopic eczema
There is a strong genetic/inherited susceptibility to developing atopic conditions including eczema. The genetic abnormalities affect the effectiveness of the permeability barrier of the skin surface and the control of the immune system, resulting in allergies. Eczema is easily irritated and aggravated by soaps and scents, cold and extremes of dryness or humidity. Increased colonization of the skin by bacteria can flare eczema. Emotional stress is an important trigger in many individuals.
Role of allergy
Atopic Eczema can be triggered by an allergy to a range of foods or airborne allergens. Allergy to foods may aggravate eczema in 30-40% of children. In older children and adults food allergy is much less common while house dust mites, pollens and animal furs may be significant provoking factors. Testing for allergic triggers is very unreliable as positive skin tests can be found in 70-80% of patients but this does not tell how much the allergy contributes amongst the many other factors.
Treatment aims to suppress inflammation with corticosteroid creams. There are 4 categories from weak (Hydrocortisone) through potent (Betnovate) to super potent (Dermovate). Recently non-steroid creams (Protopic and Elidel) have become available. Regular use of moisturisers can soothe the itch. Infection requires antibiotics. In people with definite allergic provocation, avoidance of allergens can be helpful.