What are the causes of eczema?

As previously mentioned, there are several types of eczema. It is important to distinguish between them, as the management approach differs for each. These types of eczema have different origins. Among them, we can mention:

• Firstly, we have atopic eczema which evolves in flare-ups. It is caused by a genetically originated atopic predisposition (in most cases, a child affected has a parent who is also affected). Atopy refers to a person's tendency to develop a allergic reaction to normal environmental elements (animal hair, dust, pollen...), which do not cause problems for the rest of the population. Studies have highlighted abnormalities affecting the gene coding for filaggrin as well as other molecules necessary for the proper functioning of the horny layer. This atopy is caused by a dysfunction of the skin barrier (due to a lack of sebum, lipids and cell adhesion molecules production) which can no longer play its protective role. This dermatosis, very common in children, is often associated with allergic rhinitis, food allergies and asthma attacks. In most cases, atopic eczema disappears during childhood. However, in rare cases, it can persist into adulthood. The prevalence of atopic eczema is increasing over the years. Environmental factors such as pollution or an increase in hygiene levels could explain this rise. Indeed, increased hygiene during childhood would favour an atopic predisposition as the child is very little exposed to pathogens ;

• If you do not normally suffer from eczema and suddenly an eczema lesion appears, it could becontact eczema. Contact eczema is an acquired inflammatory skin disease (meaning there is no inherent atopic genetic predisposition) that develops following skin contact with an allergen. It is a reaction that disappears when the offending products are removed;

• Thenummular eczema (or discoid) is a lesser-known form of eczema. Clinically, it is characterised by well-defined round or oval erythematous patches. The lesions are generally located on the upper and lower limbs, including the backs of the hands and feet. The etiology of this type of eczema is multifactorial and poorly defined. However, there are risk factors such as dry skin (xerosis), irritants (detergents, harsh washing products) and excessive consumption of tobacco and alcohol;

• Dyshidroticeczema is a fairly common form of eczema. It is characterised by vesicular lesions on the palmoplantar epidermis (edges of fingers or toes - palms of hands - soles of feet). These vesicles are filled with a clear fluid and are accompanied by a fierce itch. There is a strong association between allergies and dyshidrotic eczema. Therefore, lesions appear more frequently in people with contact eczema, atopic eczema or those with allergies (hay fever). There are certain predisposing factors such as pollen, stress, prolonged contact with water, nickel (found in jewellery, keys etc) or even cobalt (found in medical equipment, dishes, paints etc);

• Recent studies have demonstrated the frequent presence of zinc deficiency in cases of atopic dermatitis: this is known asdeficiency eczema. Indeed, zinc is a trace element that plays a crucial role in immune balance. Zinc supplementation in individuals with a deficiency has shown symptom improvement after 8 weeks of treatment.

Dermatologist Dr. Bethsabée LEVY GAREL explains that it's important to distinguish between eczema and irritant dermatitis: "Unlike eczema, which is an allergic skin disease that only develops in certain individuals, irritant dermatitis does not involve an allergic mechanism. Indeed, it is due to the intrinsic properties of the product and occurs in all individuals exposed to the product."