High-Risk Dysplasia, Multifocal Attachment Are Independent Predictors of Recurrence in SNIP

Background: Sinonasal inverted papilloma (SNIP) carries approximately a 10% risk of malignant transformation and a tendency to recur. The prognostic significance of dysplasia in these lesions has not been well studied. Objective: To evaluate the relationship between dysplasia grade, tumor attachment pattern, and recurrence-free survival (RFS) in the largest cohort to date examining the prognostic significance of dysplasia. Design: Multi-institutional, retrospective cohort study. Methods: SNIP cases treated at 7 institutions between 2002 and 2023 were identified retrospectively. Dysplasia was classified into 3 groups: no dysplasia, low-risk (mild or moderate dysplasia), and high-risk (severe dysplasia or carcinoma-in situ). Tumor attachment was classified as unifocal or multifocal. The primary end point was RFS, analyzed using Kaplan–Meier methods and Cox proportional hazards regression. Results: 448 patients were included with a mean age of 58 ± 13.5 years, and 65.4% wer more...