Can one have contact eczema on top of atopic eczema?

Atopiceczema, also known as atopic dermatitis, is a chronic skin disorder caused by a genetic predisposition. Studies have shown that affected individuals often have mutations in the genes coding for filaggrin and other proteins essential for the integrity of the stratum corneum. This leads to a dysfunction of the skin barrier, resulting in significant insensible water loss - and therefore constant skin dryness (xerosis) - and an increased susceptibility to penetration by environmental allergens.

It has also been demonstrated that individuals suffering from atopic dermatitis secrete moreimmunoglobulin E (IgE) than others. IgE is a class of antibodies synthesised in response to antigens. This triggers disproportionate immune responses when the body comes into contact with common allergens (dust, pollution, animal fur...). Atopic eczema is a skin condition of an inflammatorynature. It results in skin dryness, blisters, as well as red lesions, which evolve in flare-ups.

Contacteczema is a skin allergic reaction that occurs when the skin comes into contact with a specific allergen. This could be pollen, a fragrance, an essential oil, etc. Contact eczema presents in the same way as atopic eczema and is characterised by fluid-filled blisters, red patches and itching.

Contact eczema is localised to the area of the skin that comes into contact with the allergenic substance. This contact can be direct or indirect. For instance, when the allergen is carried by the air (pollen, dust...), the contact is said to be airborne. If the allergen is transmitted by the hands, it is referred to as hand-carried contact. Finally, if the symptoms only appear after the skin has been exposed to UV rays, the eczema is classified as photo-triggered.

Yes, it is possible to have contact eczema on top of atopic eczema. Indeed, contact dermatitis can be facilitated by pre-existing atopic eczema. Therefore, a person with atopic dermatitis is quite likely to develop contact dermatitis, following exposure to a specific allergen. A contact allergen that could exacerbate or make the atopic eczema more resistant will be investigated if the person responds less effectively to treatment, if the eczema patches are more localised than usual, or if they are located in a different place.

How to alleviate contact eczema and atopic eczema?

Even though these two forms can coexist, it's important to remember that contact eczema and atopic eczema have different origins and are not treated in the same way. In the case of contact eczema, the first step is to identify the allergen. Once the triggering factor has been determined by the dermatologist-allergist, it is necessary to avoid it to prevent recurrence. The patches caused by contact eczema are soothed by corticosteroid-based treatments.

The treatment of atopic dermatitis is more complex. Indeed, it is rare to accurately determine what the triggering factors of the disease are, given that the skin is sensitive to all types of external aggression. The treatment relies on the daily application of emollient care to strengthen the skin barrier and anti-inflammatory care during flare-ups. As with contact eczema, this is most often dermocorticoids.

• GOLDENBERG G. & al. Eczema. The Mount Sinai Journal of Medicine (2011).

• BORRADORI L. & al. Dermatologie et infections sexuellement transmissibles. Elsevier Masson (2017).