Eczema: what are the symptoms?

Theatopic eczema, also known as atopic dermatitis, is a chronic inflammatory disease that progresses in flare-ups. It can affect anyone, but it predominantly affects children and infants (1 in 10 children are affected).

There exists a genetic predisposition that favours the atopic nature of this disease: over 50% of affected individuals have a parent who is also affected. Indeed, research has highlighted abnormalitiesaffecting the gene coding for filaggrin, as well as other molecules necessary for the integrity of the corneal layer.

This atopy is caused by a deficiency in the production of sebum, lipids, and cell adhesion molecules, leading to amalfunction of the skin barrier which can no longer fulfil its protective role.

To note : atopy refers to an individual's tendency to develop aallergic reactionto normal environmental elements (animal hair, dust, pollen...), which do not cause any problems for the rest of the population.

There exist various types of eczema (contact eczema, nummular eczema etc), but the primary one is atopic eczema caused by a dysfunctional skin barrier. This barrier, no longer being impermeable, allows water to escape from the epidermis and external elements to enter, thus causing various symptoms and complications.

Atopic eczema is characterised by flare-up periods interspersed with remission periods. An atopic skin is the source of several symptoms.

Eczema skin lesions.

Red and inflammatory, eczema lesions appear during flare-ups. Generally, they affect the face, neck, but also the body's folds (elbow folds - knee folds). Eczema lesions progress through 4 stages.

1. The erythematous phase.

   It is characterised by red lesions and warm, signs of the inflammatory response. These are more or less extensive and their edges are poorly defined. At the site of the lesions, a thickening of the skin is observed. These lesions are accompanied by a sensation of intense itching.

2. The vesicular phase.

   A few hours later, small vesicles filled with clear fluid appear at the site of the red lesions and the itching persists.

3. The following phase.

   Eczema lesions are highly pruritic, and scratching can rupture the vesicles. Therefore, the weeping phase is characterised by a rupture of the vesicles, either spontaneously or following scratching.

4. The crusty or desquamative phase, followed by healing with or without scarring.

   As a result of scratching, chronic lesions may appear, such as a thickening of the skin (lichenification) or prurigo. Furthermore, scratching can lead to a bacterial infection by Staphylococcus aureus, resulting in the formation of impetigo.

Itching.

Eczema lesions are accompanied by a significant itching sensation. This itching sensation leads to sleep disturbances and irritability.

Extremely dry skin.

An atopic skin is constantly very dry , even outside of flare-up periods. This extreme dryness is referred to as "cutaneous xerosis". Indeed, due to a dysfunctional skin barrier, water easily evaporates from the epidermis. This results in dry and uncomfortable skin. Certain external factors, such as prolonged contact with water or the use of unsuitable products, exacerbate xerosis. Emollients play a key role in managing eczema, as they help to maintain less dry and more comfortable skin.

Note : Contacteczema is an acquired inflammatory skin disease that triggers after contact with an allergen. In this case, the eczema lesions are the same as those for atopic eczema. The only difference is that the lesions cease when the offending product is removed. Moreover, contact eczema is not characterised by dry skin, as it does not result from a malfunction of the barrier function.

• Institut National de la Santé et de la Recherche Médicale (INSERM) - Dermatite atopique. https://www.inserm.fr/dossier/dermatite-atopique-eczema-atopique/

• ORCHARD D. & al. Eczema management in school-aged children. Australian Family Physician (2017).