New paradigm for the roles of fungi and eosinophils in chronic rhinosinusitis

Abstract

Chronic rhinosinusitis represents a challenge with its poorly understood pathophysiology and limited treatment options. Potential roles of fungi and eosinophils in the etiology and pathophysiology of chronic rhinosinusitis are summarized. Previously, the fungal role in chronic rhinosinusitis was limited to the rare subgroup, allergic fungal rhinosinusitis. Critical examination of earlier diagnostic criteria for allergic fungal rhinosinusitis reveals limitations. By using updated diagnostic standards and novel sensitive techniques to detect fungi, a higher number of patients can now be diagnosed with fungal rhinosinusitis. A novel non-IgE-mediated immunologic mechanism in chronic rhinosinusitis patients links the predominant eosinophilic inflammation to certain fungi. Overall, these new findings have implications for surgical and medical approaches, including anti-inflammatory and antifungal medications. Several classification schemes and diagnostic criteria describe chronic rhinosinusitis and make comparisons difficult. Preselection of patient groups within the chronic rhinosinusitis population and the lack of sensitive diagnostic techniques have prevented a full understanding of the syndrome complex of chronic rhinosinusitis. New results suggest a broader role for fungi in the pathophysiology of chronic rhinosinusitis, linking the eosinophilic inflammation to the presence of certain molds in the nasal and paranasal cavities. Although fungi are commonly found in nearly everyone, only chronic rhinosinusitis patients respond to them with an eosinophilic inflammation. These findings support a shift in the etiologic understanding of chronic rhinosinusitis away from a bacteriologic infectious pathogenesis to a fungal-driven inflammatory pathophysiology. Herein, the authors review earlier studies and describe an updated view on an old paradigm.