CRSwNP is different from CRSsNP by the presence of nasal polyps consisting of a large quantity of extracellular oedema with the presence of a dense inflammatory cell infiltrate [49, 50], which is characterized in about 80% of the Caucasian CRSwNP patients, by activated eosinophils [51, 52] and is associated with a predominant Th2 cytokine profile (IL-4, IL-5, IL-10, eotaxin) [53, 54]. Here, IL4 is linked to chronic rhinosinusitis with nasal polyps.