Histological analysis
Mucosal tissues from patients with CRS were obtained from nasal polyps or the uncinate process. Tissues were immediately fixed in 10% formalin, embedded in paraffin, and cut into thin sections. Sections were stained with hematoxylin–eosin to differentiate CRS into various eosinophilic phenotypes. Representative HE staining pictures of Non-eCRS and ECRS were shown in Supplementary Fig.1A. The numbers of eosinophils and total inflammatory cells beneath the epithelial surface per high power field (HPF) (x400) were quantified by 2 independent researchers and the percentage of eosinophils in total infiltrating inflammatory cells (eosinophils percentage) was calculated. Five fields were randomly selected, then the average percentage was analyzed. According to previous studies of ECRS in China, we defined ECRS as eosinophil percentage exceeding 10%, as proposed by Cao et al32.
At the same time, the histological patterns of each patient were evaluated according to histopathological characteristics referring to basement membrane thickening, goblet cell hyperplasia, subepithelial edema, submucous gland formation, eosinophils infiltration, fibrosis and atypical cells by 2 independent researchers. Briefly, there were four main classifications: edematous, eosinophilic CRS with a great number of eosinophils, goblet cell hyperplasia, thickening of the basement membrane; CRS characterized by numerous seromucous glands and ductal structures; fibroinflammatory CRS, lack of stromal edema and goblet cell hyperplasia, frequently showed evident dilated vessels and a great number of fibrocytes; atypical CRS with distinct stromal cells that were bizarre and atypical. Representative HE stainings of the histologic pattern was shown in Supplementary Fig. 1B.