Histopathological Evidence of Persistent Remodeling in Recurrent Acute Rhinosinusitis

Background Recurrent acute rhinosinusitis (RARS) is traditionally regarded as an episodic infectious disorder with complete mucosal recovery between attacks. However, histopathological evidence supporting this assumption is limited. Objective To evaluate whether mucosal inflammatory and remodeling changes persist during the asymptomatic interval in patients with RARS compared with nonsinusitis surgical controls. Methods In this prospective observational study (January 2023–December 2025), sinonasal mucosal specimens obtained during functional endoscopic sinus surgery were analyzed from adults with RARS and nonsinusitis surgical controls. Patients with chronic rhinosinusitis, active infection, or recent systemic corticosteroid use were excluded. Histopathological outcomes included neovascularization, submucosal fibrosis, inflammatory infiltration, and basement membrane thickness. Results Twenty-four patients were included (17 RARS; 7 controls). Compared with controls, RARS specimens demonstrated higher neovascularization scores (median 2.0 vs 1.0; median difference, 1.0; 95% CI, 0.2-1.8; P = .034) and greater submucosal fibrosis (median 2.0 vs 1.0; median difference, 1.0; 95% CI, 0.1-1.9; P = .047). Inflammatory infiltration was numerically higher but did not reach statistical significance (median difference, 0.5; 95% CI, −0.1 to 1.1; P = .053); severe inflammation was observed only in RARS specimens (35% vs 0%). Basement membrane thickness did not differ between groups. Higher symptom burden (SNOT-22 ≥ 57.5) was associated with greater fibrosis ( P = .041). Conclusion In this surgically treated cohort, RARS was associated with persistent mucosal neovascularization and fibrosis despite clinical quiescence. These findings suggest that RARS may involve ongoing interepisode tissue remodeling rather than a purely episodic process.