Allergic fungal rhinosinusitis and eosinophilic mucin chronic rhinosinusitis: Differential diagnostic criteria. A two-center comparative study following STROBE methodology

Objectives: Allergic fungal rhinosinusitis (AFRS) and eosinophilic mucin chronic rhinosinusitis (EMRS) are two forms of chronic sinusitis distinguished by the presence (AFRS) or absence (EMRS) of fungal elements in sinus mucin. Detection of the fungal elements, however, is complex and it is difficult to say whether EMRS is in fact an entity distinct from AFRS. The aim of the present study, based on a retrospective series of AFRS and EMRS, was to identify the specific clinical and radiological elements distinguishing between the two.

Materials and methods: A 2-center retrospective observational study following STROBE guidelines included patients managed for AFRS or EMRS between 2009 and 2022. Clinical, mycological, pathologic and radiological data were collected. Type of treatment and disease progression were also analyzed. Intergroup comparison used Student's test for mean values of quantitative variables, with calculation of P-values, and Pearson's Chi² test or Fisher's exact test for categoric variables, with calculation of relative risk and 95% confidence intervals.

Results: The AFRS group comprised 41 patients and the EMRS group 34. Demographic data were comparable between groups. EMRS showed a higher rate of asthma (79.4 vs. 31.4%; P<0.001), more severe nasal symptomatology (rhinorrhea, P=0.01; nasal obstruction, P=0.001), and more frequent bilateral involvement (85.3 vs. 58.5%; P=0.021). AFRS showed more frequent complications (19 vs. 0%; P=0.006). Radiologically, mucin accumulation was greater in AFRS, filling the sinus in 84.2% of cases, versus 26.3% (P<0.001), with more frequent sinus wall erosion (19 vs. 5.8%; P=0.073). The recurrence rate was higher in EMRS: 38.2 vs.21.9% (P=0.087).

Conclusion: The present retrospective study found a difference in clinical and radiological presentation between AFRS and EMRS, with EMRS more resembling the presentation of severe nasal polyposis.