Inflammatory infiltrate and mucosal remodeling in chronic rhinosinusitis with and without polyps: structured histopathologic analysis

Background: Chronic rhinosinusitis (CRS) is commonly classified into CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). Structured histopathologic reporting has the potential to identify salient histologic markers to differentiate subtypes and provide insights into pathophysiologic mechanisms in CRS. Methods: A structured histopathology report of 13 variables was prospectively employed to analyze ethmoid sinus tissue removed during endoscopic sinus surgery for 99 patients, including 43 CRSsNP and 56 CRSwNP. These variables were compared in association with presence of nasal polyps, radiographic computed tomography scores (Lund-Mackay Score [LMS]), subjective symptoms scores (SNOT-22), duration of CRS, comorbid asthma, and atopy. Results: Overall inflammation did not differentiate between CRSsNP and CRSwNP (p < 0.26). Compared to CRSsNP, CRSwNP had statistically significant increase in basement membrane thickening (76.8% vs 48.8%, p < 0.004), subepithelial edema (19.6% vs 2.3%, p < 0.01), fibrosis (58.9% vs 27.9%, p < 0.002), hyperplastic/papillary changes (12.5% vs 0.0%, p < 0.016), eosinophilia (41.1% vs 18.6%, p < 0.047), and eosinophilic aggregates (30.4% vs 11.6%, p < 0.022). Higher LMS was associated with increased eosinophilia (p < 0.001), eosinophil aggregates (p < 0.000), inflammation (p < 0.023), basement membrane thickening (p < 0.037), hyperplastic/papillary changes ( p < 0.040) and fibrosis ( p < 0.000). SNOT22 scores were not associated with any histologic parameters. Conclusion: Significant histopathologic differences were evident in patients with CRSwNP and CRSsNP. No single feature reliably differentiated between the 2 subtypes, underscoring the heterogeneity of CRS and limitation of this phenotypic classification system. Eosinophilic aggregates were associated with significantly worse disease, possibly signifying a unique subtype. Further studies are needed to understand the relationship of histopathologic features to disease outcome. (C) 2017 ARS-AAOA, LLC.