Nasal eosinophilia in pediatric non-allergic rhinitis: correlation with clinical severity scales

BACKGROUND: Non-allergic rhinitis syndrome (NAR) is a chronic rhinitis characterized by the significant absence of an allergy history, negative skin prick test results, and normal serum IgE levels. Nasal cytology is a valuable diagnostic method that enables qualitative and quantitative assessment of inflammatory cells - including eosinophils, neutrophils, mast cells, and lymphocytes - in the nasal mucosa. This study aimed to evaluate the levels of nasal eosinophilia in a pediatric NAR population and to evaluate the correlation of this local inflammatory biomarker with clinical severity scales such as ARIA and PRQLQ. METHODS: This prospective, cross-sectional study included 103 children aged 5-18 years: 53 with NAR and 50 healthy controls. Symptom duration and severity were classified according to ARIA 2019 criteria. The Paediatric Rhinitis Quality of Life Questionnaire (PRQLQ) was used for quality of life assessment. Nasal cytology specimens were collected by nasal swab from the middle meatus and the eosinophil percentage was calculated by counting a total of 100 cells in the area of highest cell density. RESULTS: A total of 103 children were enrolled: 53 NAR patients and 50 healthy controls. Median age was 10 (8-13) years in the study group and 11 (8-14) years in the control group. Family history of allergy was significantly higher in the study group (30.2%) compared to controls (12.0%) (p = 0.024). Median nasal eosinophil level was 7.0 (3.5-15.5) in the study group and 0 (0-3.0) in controls; the difference was statistically significant (p < 0.001). The nasal eosinophil cut-off value was determined as 3.5%. No significant difference was found between nasal eosinophil groups (< 3.5% and ≥ 3.5%) and any PRQLQ subscale or total score (p > 0.05). CONCLUSIONS: Nasal cytology may serve as a simple, non-invasive diagnostic tool to identify NAR subtypes and to determine clinical severity in pediatric patients.