Role of Narrow Band Imaging Endoscopy in Preoperative Evaluation of Laryngeal Leukoplakia: A Review of the Literature

Introduction: Leukoplakia is a precancerous lesion considered to be within the spectrum of histopathological results from parakeratosis, through stages of dysplasia to invasive cancer. Narrow band imaging (NBI) endoscopy has been introduced to improve early diagnosis of benign and malignant laryngeal lesions. The aim of this literature review was to evaluate the accuracy of preoperative evaluation of vocal fold leukoplakia with NBI endoscopy in comparison with histology. Methods: A systematic review of the literature was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, using 3 different databases: PubMed, Embase, and Scopus. The included articles in the systematic review were identified combining each of the following terms: "narrow band imaging" OR "NBI," [AND] with each of these terms: "laryngeal leukoplakia," OR "vocal fold leukoplakia," OR "vocal cord leukoplakia." Results: The articles that fully met the inclusion criteria were 5 case series, conducted between January 2010 and February 2018, and published between 2017 and 2019. The selected articles included 312 patients (86% males and 14% females), affected by 382 vocal cord leukoplakia, evaluated with NBI endoscopy and that underwent surgical microlaryngoscopy with biopsy. Based on the studies included in the review, accuracy of NBI in predicting malignancy within leukoplakia ranged from 81% to 97.8%, demonstrating to be an accurate method to predict the risk of malignant transformation of vocal fold leukoplakia. Conclusion: Narrow band imaging can help otolaryngologists in the decision-making process on the necessity to perform a biopsy and transoral surgery or long-term follow-up. Larger studies are necessary to confirm the high association of NBI evaluation of the epithelium surrounding the leukoplakia with the histological diagnosis.