HPV RNA in-situ hybridization as a diagnostic aid in papillary laryngeal lesions

Objectives: In the larynx, differentiating squamous papillomas from de-novo papillary squamous dysplasias or squamous cell carcinomas (SCC) has significant consequences for management. Overlapping clinical presentations and cytologic changes across the spectrum of papillary lesions presents diagnostic challenges for otolaryngologists and pathologists. In this study, we evaluate whether ribonucleic acid (RNA) in-situ hybridization (ISH) for low-risk and high-risk human papillomavirus (HPV) can help distinguish these lesions. Methods: We constructed tissue microarrays from 97 papillary laryngeal lesions, including 61 squamous papillomas, two papillomas with dysplasia, two SCCs-ex papilloma, 14 papillary squamous dysplasias, and 18 papillary SCCs identified at the Johns Hopkins Hospital between 2000 and 2017. We performed RNA ISH using probes for low-risk and high-risk HPV types. Results: Low-risk HPV RNA was identified in 55 benign papillomas (90%), two papillomas with dysplasia (100%), and two SCCs-ex papilloma (100%) but was absent in de-novo papillary dysplasias and SCCs (0%). High-risk HPV RNA ISH was positive only in four papillary SCC (22%). Overall, low-risk HPV RNA ISH was 90% sensitive and 89% specific for benign papillomas with a positive predictive value of 93% and negative predictive value of 84%. In contrast, high-risk HPV was 20% sensitive for SCC. Conclusion: Low-risk HPV RNA ISH is a useful diagnostic adjunct for distinguishing laryngeal squamous papillomas from papillary squamous dysplasia and SCC. However, it is not entirely specific for benign processes as it is also retained in papillomas with dysplasia and SCCs-ex papilloma. Because high-risk HPV is rare in papillary laryngeal lesions, high-risk HPV RNA ISH has limited utility. Level of Evidence: Level 4. Laryngoscope, 130:955–960, 2020.