Exploring the role of nasal cytology in chronic rhinosinusitis

Objective. Characterising the eosinophilic profile represents the main step in chronic rhinosinusitis (CRS) endotyping. The aim of the study is to verify the correlation between different methods for tissue eosinophilia quantification. Methods. 33 CRS patients undergoing endoscopic sinus surgery and 30 controls undergoing non-CRS surgeries were enrolled. Blood venous sampling, nasal biopsy on uncinate process (UP), nasal cytology on inferior turbinate (IT) and middle meatus (MM) were performed. Results. Differences in eosinophil count in blood (P=0.0001), UP (P<0.0001), IT (P = 0.01) and MM (P = 0.0006) were significant between CRS cases and controls. A weak correlation was found between UP and blood eosinophil count (r = 0.34, P = 0.006) and between UP and IT eosinophil count (r = 0.30, P = 0.017). Moderate correlation between UP and MM (r = 0.51, P < 0.0001) was shown. ROC analysis predicted eosinophilic CRS with an overall low sensitivity. Once allergic patients were excluded from the analysis, the sensitivity decreased for sampling on IT and increased for MM sampling. Conclusions. This study suggests that MM cytology gives more accurate information on the degree of tissue eosinophilia. Replication in wide and unbiased cohorts is necessary to verify these results and define accurate thresholds.