Atopic dermatitis (AD) is a complex disease, whose definition is still problematic, behind the undeniable progress of the pathogenetic knowledge and treatment approaches.1 A common denominator of the multiple phenotypes and endotypes remains an exaggerated inherited hypersensitivity reaction to normally well tolerated stimuli, as the etymology suggest, from the ancient Greek ἄτοπος (átopos), made of ἀ- (alpha-privative) + τόπος (tópos, ‘place’), meaning the ‘state of being out of place’.
