Feature Review:

Eczema: An Overview & Update

Vincent St Aubyn Crump – February 2009

Introduction

Atopic eczema or atopic dermatitis in children, along with the other atopic diseases, asthma and hay fever (allergic rhinitis), has considerably increased in Western population over the last 30 years (almost tripled). The prevalence is about 10-20% of children under the age of 14 years, and 2-10% in adults. This very common condition has a significant emotional, social and economic impact on the sufferer and his/her family, and thus it is important for all healthcare clinicians to be familiar and up-to-date with the disease and its therapeutic management based on “Evidence”.

Definition

Stedman’s medical dictionary defines Eczema as: Generic term for inflammatory conditions of the skin, particularly with vesiculation in the acute stage, typically erythematous, edematous, papular, and crusting; followed often by lichenification and scaling and occasionally by duskiness of the erythema and, infrequently, hyperpigmentation; often accompanied by sensations of itching and burning; the vesicles form by intraepidermal spongiosis; often hereditary and associated with allergic rhinitis and asthma.

This definition, like most definitions of eczema, to a large extent is defining atopic eczema, which will also be the focus of this paper, but for completeness and to assist in differentiating AD from the other types of eczema, the other types of eczema will be mentioned in the differential diagnosis of Atopic Eczema towards the end of this paper as well.

Some writers use the classification of endogenous eczema to mean atopic eczema and exogenous to include irritant and allergic contact dermatitis. Others classify the patients with AD who are allergic as extrinsic and those without as intrinsic eczema.

“Atopy” is defined as a form of allergy in which there is a hereditary or constitutional tendency to develop hypersensitivity reactions. This tendency to produce specific IgE responses to allergens is associated with “atopic” eczema, but up to 40% of individuals with the disease phenotype may not be atopic. This makes continued use of the term atopic eczema somewhat problematic. A more useful nomenclature of Atopic eczema / dermatitis syndrome (AEDS), which was proposed by the European Academy of Allergology and Clinical Immunology (EAACI) Nomenclature Task Force in 2001 has been updated by the World Allergy Organization in 2004.( Ref Johansson et al, JACI, 2004). The new nomenclature is based on the mechanisms that initiate and mediate allergic reactions. The term “eczema” is proposed to replace the provisional term Atopic eczema / dermatitis syndrome (AEDS). The term ‘atopy’ should not be used until an IgE sensitization has been documented by IgE antibodies in the blood of a person or a positive skin prick test to common environmental allergens such as dust mites, pollens , or cat. The term eczema can therefore be split into ‘atopic eczema’ and non-atopic eczema’.

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