In research setting, the diagnosis of eosinophilic CRSwNP is either based directly on tissue eosinophilia (>5 eosinophils/high power field or indirectly on ECP/myeloperoxidase (MPO) ratio (>1) determined on nasal biopsies [26, 27, 29]. This evidence concerns the gene MPO and Increased total eosinophil count.