Histopathological and clinical analysis of chronic rhinosinusitis by subtype

Background: Chronic rhinosinusitis (CRS) encompasses diverse phenotypic expression. Clinical and histological differences suggest 4 CRS subtypes: eosinophilic CRS with and without nasal polyps (eCRSwNP, eCRSsNP, respectively) and non-eosinophilic CRS with and without nasal polyps (neCRSwNP, neCRSsNP, respectively). The mucosal basement membrane (BM) and cilia are believed to play roles in CRS pathogenesis by impacting mucociliary clearance and immune barriers. This study aimed to identify clinical, surgical, and histopathological subtype differences to further elucidate disease mechanisms. Methods: Ethmoid tissue from 33 adult CRS patients and 7 controls was obtained during endoscopic sinus or other sinonasal surgery (controls) and analyzed by light and transmission electron microscopy for BM thickness and presence of cilia. CRS patients were categorized into the 4 subtypes, and 22-item Sinonasal Outcome Test (SNOT-22) score, endoscopy, computed tomography (CT), and surgical data were compared and analyzed for association with histopathology measures. Results: CRS subtypes could be distinguished by CT score and surgical data, with eCRSwNP patients exhibiting greatest disease severity. Whereas eosinophilia was associated with absence of cilia, nasal polyposis showed no association with surgical or histopathological measures. No significant difference in BM thickness was found between controls and CRS subtypes, but distinctions were found regarding cilia, which were less common in eosinophilic subgroups compared to controls and neCRSsNP patients. Conclusion: CRS subtypes exhibit some differentiating histopathological and surgical features. The absence of cilia appears to have an important role in the eosinophilic subgroups. Further histologic evaluation is warranted to evaluate for possible subtype-specific treatment targets or prognostic markers.