Introduction: Allergic fungal rhinosinusitis (AFRS) is a noninvasive type of fungal rhinosinusitis (FRS) that is diagnosed by fulfilling five diagnostic criteria. Objectives: We aimed to study the fungal etiology of AFRS and to evaluate the prevalence of AFRS among patients with CRS with nasal polyposis (CRSwNP) that underwent endoscopic sinus surgery (ESS) at Sohag University Hospital.
Patients and Methods: A prospective study that involved all patients presented to Otorhinolaryngology Department, Sohag University Hospital, Egypt, with nasal polyposis and were candidate for ESS over a one year period. CT scan was done for all. Histopathological examination of removed polyps and allergic mucin (AM) was done using hematoxylin & eosin (H&E), periodic Acid schiff (PAS) and Gomori methanamin silver (GMS) stains. Statistical analysis was carried out with the Statistical Software Package Standard (SPSS). Results: In 17/61 patients, AM was detected, 12/61 of them (19.7%) showed no fungal hyphae and were diagnosed eosinophilic mucin rhinosinusitis (EMRS). In the remaining 5/61 (8.2%) cases fungal hyphae were seen and diagnosed as AFRS. 41/61 (67.2%) patients didn't show neither AM nor fungal hyphae and diagnosed as CRSwNP. In 2/61 (3.3%) we detected fungal hyphae both on the surface of polyp mucosa and invading the tissue and diagnosed as chronic invasive fungal rhinosinusitis (CIFRS). This finding is unique in the literature. The remaining one patient (1/61=1.6%) was diagnosed to have inverted papilloma. Conclusion: No significant association between AM and fungal hyphae, only 5/17 (P=0.09) patients with AM fulfill the diagnostic criteria of AFRS. AFRS is more appropriately termed eosinophilic mucinous rhinosinusitis. Histopathological examination of removed polyps with fungal stains is essential as it might detect fungal invasion and change the policy of management.