IL4 and chronic rhinosinusitis with nasal polyps: Type-2 inflammation plays a crucial role in CRSwNP pathogenesis and represents the most common endotype characterized by high levels of specific interleukins (IL-4, IL-13, IL-5), high tissue and blood eosinophilia (B-EOS) and high blood levels of IgE and of the exhaled fraction of nitric oxide (FENO) [2].