The characteristics of sinonasal inverted papilloma and recurrence factors: An analysis of 207 cases.

Objectives: Sinonasal inverted papilloma (IP) is a rare and benign tumor that affects the nose and sinuses. This tumor has a recurring nature and can be associated with malignancy or transform into a malignant lesion. Various factors have been proposed as potential recurrent and malignancy risk factors in sinonasal IP. This study examines some of these factors and the relationship between tumor location and recurrence and malignancy. Methods: A retrospective analysis was conducted on patients diagnosed with IP for 10 years or more, assessing the patients' demographic statistics and intraoperative observations. Additionally, CT scan results of the patients were investigated. Results: Finally, 207 patients with an average age of (52.0 ± 13.8) years were included in the study. A hundred and fifty-five (74.9%) of patients were male and the most substance abuse was tobacco (72, 34.8%). Fifty-five (26.6%) patients had a recurrence and 21 (10.2%) patients showed malignancy or dysplastic changes. The most common site of the tumor was the maxillary sinus (131, 63.3%). Conclusions: Long-term follow-up of IP patients is necessary due to the risk of recurrence and malignancy. The probability of recurrence was higher in cases where the tumor involved the frontal sinus or multisite attachment. Therefore, for accurate diagnosis of this tumor and complete resection of the lesion, especially in cases where achieving a free margin may be challenging, the intraoperative frozen section seems necessary.