The concept of atopy
Atopic dermatitis is not an allergy
The word "atopy" is derived from the Greek "a" meaning "without" and "topos" meaning "place".
"Without a place" is a perfect way to describe this disease, which is difficult to understand.
Atopy is a genetic predisposition to allergies, known as the atopic family history. Almost 80% of children with eczema have a family history.
Atopic dermatitis is a chronic inflammatory skin disease
Atopic patients (50 million people affected in Europe, up to 20% of children worldwide) have defective skin permeability and a hyperreactive and unbalanced immune system. The skin is dry, sensitive and hyperreactive.
Filaggrin, a protein of the skin which ensures adhesion between cells in the outermost layer of the skin, is deficient. In addition, the skin lacks the lipids which are naturally found on its surface and which protect it from potential allergens.
Under these circumstances, irritants found in the environment and which are usually well tolerated, such as pollen, dust and certain hygiene products, can penetrate the skin and cause a flare-up of eczema.
The disease usually occurs after (and sometimes before) the age of three months and can last between a few months and several years, depending on the child. Without proper treatment, the vicious cycle of itching settles in: the skin barrier deteriorates even further, allowing more allergens and irritants to penetrate the skin and to cause further itching.
However, few cases persist into adulthood: half the children with atopic eczema before the age of one are cured by the age of five, although the skin is still very dry in the following years.