Histopathology of Allergic Fungal Rhinosinusitis Versus Chronic Rhinosinusitis with Nasal Polyps

Objective Structured histopathology (SHP) is a method of analyzing sinonasal tissue to characterize endotypes of chronic rhinosinusitis with nasal polyps (CRSwNP). Allergic fungal rhinosinusitis (AFRS) shares several features with certain endotypes of CRSwNP. Our objective was to compare the histopathology of AFRS and eosinophilic CRSwNP to further understand whether they are separate endotypes or disease entities altogether. Methods A retrospective review of AFRS and CRSwNP patients undergoing endoscopic sinus surgery was performed. Data were collected on demographics, comorbidities, subjective and objective severity scores, and 13‐variable SHP reports. CRSwNP patients with >10 eosinophils per high‐power field (eCRSwNP) were included. Chi‐squared and t‐tests were used for statistical analysis. Results A total of 29 AFRS and 108 eCRSwNP patients were identified. AFRS patients were younger and more often Black. Symptom severity scores (SNOT‐22, Lund‐MacKay, and Lund‐Kennedy) were uniform between groups. AFRS patients had a higher rate of Charcot–Leyden crystals (41.4% vs. 10.2%; p