MDPI Acta Medica Okayama 2075-4418 12 2 2022 Clinicopathologic Analysis of Sinonasal Inverted Papilloma, with Focus on Human Papillomavirus Infection Status 454 EN Munechika Tsumura Department of Otolaryngology Head and Neck Surgery, Kagawa Rosai Hospital Seiichiro Makihara Department of Otolaryngology Head and Neck Surgery, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Asami Nishikori Division of Pathophysiology, Graduate School of Health Sciences, Okayama University Yuka Gion Division of Pathophysiology, Graduate School of Health Sciences, Okayama University Toshiaki Morito Shotaro Miyamoto Department of Otolaryngology Head and Neck Surgery, Kagawa Rosai Hospital Tomoyuki Naito Department of Otorhinolaryngology, Kagawa Prefectural Central Hospital Kensuke Uraguchi Department of Otolaryngology Head and Neck Surgery, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Aiko Oka Department of Otorhinolaryngology, School of Medicine, International University of Health and Welfare Tomoyasu Tachibana Department of Otolaryngology, Japanese Red Cross Society Himeji Hospital Yorihisa Orita Department of Otolaryngology Head and Neck Surgery, Graduate School of Medicine, Kumamoto University Shin Kariya Department of Otolaryngology Head and Neck Surgery, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Mitsuhiro Okano Department of Otorhinolaryngology, School of Medicine, International University of Health and Welfare Mizuo Ando Department of Otolaryngology Head and Neck Surgery, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Yasuharu Sato Department of Pathology, Dentistry and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Sinonasal inverted papilloma (SNIP) can recur; however, the factors related to tumor recurrence remain unclear. This study aimed to analyze risk factors, including human papillomavirus (HPV) infection, as well as other factors associated with SNIP recurrence. Thirty-two patients who were diagnosed with SNIP and underwent surgery between 2010 and 2019 were enrolled: 24 men and 8 women, with a mean age of 59.2 years. The mean follow-up was 57.3 months. Demographics and information about history of smoking, diabetes mellitus (DM), hypertension, allergic rhinitis, alcohol consumption, tumor stage, surgical approach, and recurrence were reviewed retrospectively. Specimens were investigated using polymerase chain reaction to detect HPV DNA (high-risk subtypes: 16, 18, 31, 33, 35, 52b, and 58; low-risk subtypes: 6 and 11). Seven patients (21.9%) experienced recurrence. HPV DNA was detected in five (15.6%) patients (high-risk subtypes, n = 2; low-risk subtypes, n = 3). Patients with recurrence of SNIP had a higher proportion of young adults and displayed higher rates of HPV infection, DM, and advanced tumor stage than those without recurrence. HPV infection, young adulthood, DM, and advanced tumor stage could be associated with a high recurrence rate, which suggests that patients with these risk factors could require close follow-up after surgery. No potential conflict of interest relevant to this article was reported.