ABSTRACT Background Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare necrotizing vasculitis involving upper‐ and lower‐airways. Despite biologics, sinonasal disease often persists. Evidence on ENT trajectories under anti‐IL5 treatment and role of endoscopic sinus surgery (ESS) remains limited and is often described without standardized assessment tools. This study provides a systematic, multidimensional evaluation of sinonasal outcomes under biologic therapy and analyzes the role of ESS in a real‐life cohort. Methods We retrospectively analyzed 52 EGPA patients with a 24‐month follow‐up on mepolizumab. Sinonasal disease was assessed by Nasal Polyp Score (NPS), Lund–Kennedy Score (LKS), Lund–Mackay score (LMK), and SNOT‐22, while systemic activity was assessed by Birmingham Vasculitis Activity Score (BVAS). Patients were stratified by mepolizumab regimen (100 mg, 300 mg, and step‐down ). Predictors of adjunctive ESS were explored through multivariate logistic regression. Results Systemic remission occurred in >90% of patients, with marked eosinophil suppression (median 700 → 59.5 cells/µL) and BVAS = 0. Conversely, NPS and LKS remained stable IQR: (NPS 4 3–5 → 4 2–5; LKS 6 4–8 → 5 2–7.75. Polyps persisted in 64% and mucosal edema/discharge in 92% of population. Continuous 100 mg therapy showed the greatest endoscopic improvement. Higher baseline sinonasal burden, more extensive surgical history, and mepolizumab dose variation were associated with adjunctive ESS (28.8%), whereas BVAS and eosinophils showed no correlation with ENT severity. Conclusion Sinonasal disease may persist despite systemic remission, suggesting a partially independent inflammatory niche. Comprehensive assessment should combine systemic markers with dedicated ENT evaluation, while management may require integrated biologic–surgical strategies in chronic structural disease.
Howardson et al. (2026) studied this question.