Atopic dermatitis is the most common chronic inflammatory skin disease in Italy. Very common in childhood (affecting up to 1 in 5 children), its prevalence is also increasing among adults in Western countries, affecting 2 to 5 percent of the general population. "A phenomenon perhaps due to pollution," explains Ketty Peris, full professor of Dermatology and Venereology at the Catholic University of the Sacred Heart and director of the UOC Dermatology of Fondazione Policlinico Universitario Agostino Gemelli IRCCS, "but also to the lack of exposure to bacterial agents and parasites in childhood, which results in an altered development of the immune system (this is the so-called 'hygiene theory'); in particular to be altered in atopic diseases (atopic dermatitis, allergic asthma, etc.) is the line of the Th2 immune axis, precisely the one assigned to defense against parasitic infections, which are increasingly rare in our latitudes”. "One third of adult patients," Peris explains, "have moderate-to-severe forms of atopic dermatitis, characterized by debilitating symptoms such as itching, which have a heavy impact on the patient's social and emotional sphere. And itching, which is the cardinal symptom of atopic dermatitis, can be so pervasive that it disrupts work or study (resulting in reduced work or school performance) and causes insomnia". The site of these skin manifestations changes with age: in infants and children, eczematous lesions are localized on the cheeks and extensor surfaces of the limbs; in adolescents and adults they are classically distributed at the elbow and knee creases, on the neck area, perioral and periocular region. But in severe forms, dermatitis may extend to cover the entire body surface.