Allergic Fungal Rhinosinusitis and Eosinophilic Chronic Rhinosinusitis Have Different Phenotypes in Japan

ABSTRACT Background Allergic fungal rhinosinusitis (AFRS) is a subtype of chronic rhinosinusitis driven by Types 1 and 3 allergies to fungi. In Japan, it is relatively rare and characterized by prominent eosinophilic infiltration of the sinonasal mucosa, together with eosinophilic mucin containing scattered fungi in the sinus cavity. Eosinophilic chronic rhinosinusitis (eCRS) involves similar eosinophilic infiltration and shares some clinical features with AFRS. However, the clinical differences between eCRS and AFRS remain to be fully elucidated. The aim of this study was to clarify the phenotypes of eCRS and AFRS. Methods This multicenter retrospective study enrolled patients with AFRS and eCRS and compared their clinical parameters. A cluster analysis was conducted to determine the phenotypes of the two diseases. Results AFRS patients had a younger age of onset and exhibited milder computed tomography and nasal polyp scores than eCRS patients. Total IgE was significantly higher in AFRS patients than in eCRS patients, while mucosal eosinophil counts were similar. Olfactory disturbances were significantly less severe in AFRS patients compared with eCRS patients. The cluster analysis revealed three phenotypes for AFRS: one that was distinct and independent from eCRS, representing the more classically described AFRS patients, and more the other two that shared characteristics with eCRS. Conclusions AFRS exhibits unique clinical features compared with eCRS. Cluster analysis identified three distinct AFRS phenotypes characterized by CT findings, eosinophilic inflammation, and specific IgE levels against inhaled antigens. These findings underscore the importance of differential diagnosis and personalized treatment strategies for AFRS and eCRS.