Introduction
AFRS is non-invasive fungal sinusitis recognized in 19761, which is a subset of polypoid CRS that is characterized by the presence of eosinophilic mucin with non-invasive fungal hyphae within the sinuses and a type I hypersensitivity to fungi. In 1993, Bent and Kuhn proposed the diagnostic criteria of AFRS based on the prospective study of 15 patients 2. These major criteria consist of the following: 1. Nasal polyposis; 2. Fungi on staining; 3. Eosinophilic mucin without fungal invasion into sinus tissue; 4. Type I hypersensitivity to fungi and; 5. Characteristic radiology findings with soft tissue differential densities on CT scanning and unilaterality or anatomically discrete sinus involvement. The minor criteria include bone erosion, Charcot Leyden Crystals, unilateral disease, peripheral eosinophilia, positive fungal culture and the absence of immunodeficiency or diabetes 3. The European position paper on rhinosinusitis and nasal polyps (EPOS) 2020 steering group discussed whether the term ‘eosinophilic fungal rhinosinusitis’ would be a better umbrella term but it was agreed that ‘allergic fungal rhinosinusitis’ should be retained as the principal term due to common usage, recognizing that not all cases have evidence of an allergic reaction to fungi 4.
AFRS has a high recurrence rate. It often requires two or more surgical treatments, but it is still difficult to achieve a satisfactory therapeutic effec5, 6. Delays in misdiagnosis may even lead to serious complications, including loss of smell, loss of vision, blindness, cranial nerve lesions, intracranial abscess or cavernous sinus syndrome 7-12. In serious cases, fungi may even turn into an invasive infection, resulting in patient death11. In order to investigate the incidence and improve the understanding of AFRS, we reread discharge and operative records, radiographic imaging, laboratory and pathological reports of CRS patients treated in our center from January 2015 to December 2020.