Atopic eczema is a chronic inflammatory skin condition characterised by an itchy red rash that favours the skin creases such as the folds of the elbows, behind the knees and around the neck. The morphology of the eczema lesions themselves varies in appearance from vesicles to gross lichenification on a background of poorly demarcated redness. Other features such as crusting, scaling, cracking and swelling of the skin can occur.1 Atopic eczema is associated with other atopic diseases such as hay fever and asthma. People with atopic eczema also have a tendency to dry skin, which makes them vulnerable to the drying effects of soaps.
Atopic eczema typically starts in early life, with about 80% of cases starting before 5 years of age.2 Although the word "atopic" is used when describing atopic eczema, it should be noted that about 20% of people with otherwise typical atopic eczema are not atopic as defined by the presence of positive skin-prick test reactions to common environmental allergens or through blood tests that detect specific circulating IgE antibodies.3 The word atopic in the term atopic eczema is simply an indicator of the frequent association with atopy and the need to separate this clinical phenotype from the other forms of "eczema" such as irritant or allergic contact eczema, which have other causes and distinct patterns. The terms atopic eczema and atopic dermatitis are synonymous. The term atopic eczema or just "eczema" is frequently used in the UK, whereas atopic dermatitis is used more in the US. Much scientific energy has been wasted in debating which term should be used.
Very often, no definition of atopic eczema is given in clinical studies such as clinical trials. This leaves the reader guessing as to what sort of people were studied. Atopic eczema is a difficult disease to define, as the clinical features are highly variable in morphology, body site and time. There is no specific diagnostic test which encompasses all people with typical eczema that can serve as a reference standard. Diagnosis is, therefore, essentially a clinical one.
At least 10 synonyms for atopic eczema were in common usage in the dermatology literature in the 1970s, and it is doubtful if physicians were all referring to the same disease. A major development in describing the main clinical features of atopic eczema was the Hanifin and Rajka diagnostic criteria (1980).4 These criteria are frequently cited in clinical trial articles, and they at least provide some degree of confidence that researchers are referring to a similar disease when using these features. It should be borne in mind however that these criteria were developed on the basis of consensus, and their validity and repeatability is unknown in relation to physician's diagnosis.3 Some of the 30 or so minor features have since been shown not to be associated with atopic eczema, and many of the terms, which
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