Narrow Band Imaging Improves Endoscopic Differentiation of Inverted Papillomas From Nasal Polyps

OBJECTIVE: Differentiating inverted papillomas (IPs) from nasal polyps (NPs) using white-light endoscopy (WLE) can be challenging, despite their distinct management and prognoses. Narrow-band imaging (NBI) enhances visualization of mucosal microvasculature and may improve the diagnostic accuracy of sinonasal endoscopy. This study evaluated the usefulness of NBI in differentiating IPs from NPs based on mucosal microvasculature patterns. METHODS: This retrospective study included 94 patients with histologically confirmed sinonasal lesions (61 NPs and 33 IPs) who underwent preoperative WLE and NBI. Endoscopic images were evaluated using the Bruno classification and six predefined microvasculature features: intervascular background coloration (IBC), proliferation, dilatation, tortuosity, caliber changes, and various shapes. Diagnostic performance was compared for WLE, NBI, and their combined use, with histopathology as the reference standard. RESULTS: Using the Bruno classification, most NPs demonstrated a sinonasal (SN) 3 vascular pattern (67.2%), whereas most IPs demonstrated an SN4 pattern (69.7%). Among the microvascular features, IBC and vascular dilatation were significantly more common in IPs than in NPs (p = 0.001 and p = 0.008, respectively). NBI demonstrated higher sensitivity (81.8%), specificity (91.8%), and diagnostic accuracy (88.3%) than WLE (63.6%, 85.2%, and 77.7%, respectively). Combining WLE with NBI further improved diagnostic performance, achieving a sensitivity of 90.9%, specificity of 96.7%, and accuracy of 94.7%. CONCLUSIONS: NBI improves the endoscopic differentiation of IPs from NPs by enhancing the visualization of mucosal microvasculature. Combined WLE and NBI provide the highest diagnostic accuracy and may serve as a useful adjunct in the preoperative evaluation of sinonasal lesions.