The importance of local eosinophilia in the surgical outcome of chronic rhinosinusitis: A 3-year prospective observational study

Background: Patients with chronic rhinosinusitis with/without nasal polyps (CRSwNP/CRSsNP) benefit from endoscopic sinus surgery (ESS), with an estimated success rate of 80%. At present, the influence on clinical outcome after ESS of eosinophils, eosinophilic mucin (EM), and fungal hyphae (FH) in secretions remains unclear. By delineating CRS groups and subgroups based on the finding of eosinophils, EM, and FH, differences in recurrence after ESS were investigated. Methods: A prospective monocenter study including 221 CRS patients who were unresponsive to medical treatment and underwent ESS was performed. All tissue and sinonasal secretions were microscopically examined for the presence of eosinophils, EM, and FH. Patients were followed for 3 years after surgery. Recurrence was defined according to the European position paper on rhinosinusitis and nasal polyps. Results: In total, 96 CRSwNP and 125 CRSsNP patients were included. Tissue eosinophils were found in 78% of CRSwNP patients compared with 42% in CRSsNP patients. EM was observed in 52% of the CRSwNP group versus 20% of the CRSsNP group. Furthermore, secretion analysis revealed FH in 7% of CRS. Recurrence in the total group was 22% over 3 years. CRSwNP patients with tissue eosinophilic involvement showed a recurrence rate of 48%, and those with additional EM showed recurrence in 56%. Conclusion: The presence of eosinophils in tissue or airway secretions greatly increases the risk of recurrent disease in CRSwNP patients. The finding of tissue eosinophilia and EM provides valuable information regarding the increased likelihood of CRS recurrence after ESS, whereas the finding of FH does not.