Eosinophilic mucus chronic rhinosinusitis: Clinical subgroups or a homogeneous pathogenic entity?

Background: Eosinophilic mucus chronic rhinosinusitis (EMCRS) can be subclassified using the criteria of detection of fungi in eosinophilic mucus and systemic fungal allergy. Allergic fungal sinusitis (AFS), a subgroup of EMCRS characterized by the presence of fungal allergy, is proposed to be an immunoglobulin (Ig)E-driven disease, distinct from other EMCRS subgroups. However, our recent studies cast doubt on the central pathogenic role of allergy in AFS. The purpose of this study was to examine the clinical features of EMCRS patients from the different subcategories to determine the relevance of this classification system. Method: The demographic, clinical, and immunologic characteristics of the EMCRS subgroups were examined prospectively and compared with three control groups: healthy volunteers, allergic rhinitis with fungal allergy, and chronic rhinosinusitis without eosinophilic mucus. Results. EMCRS patients with allergy were younger than those without. There was no significant difference in clinicopathologic parameters between EMCRS subgroups. As a single group, EMCRS had a more severe sinus disease compared with chronic rhinosinusitis patients. Conclusions: AFS was not clinically distinct from other subgroups of EMCRS. However, eosinophilic mucus may mark a more severe and distinct form of sinus disease.