The prognosis and recurrence rate of inverted papilloma (IP) with concomitant cellular dysplasia are not well-delineated. Demographic, clinical and imaging data of all patients who were surgically treated for sinonasal inverted papilloma (SNIP) in our center between 1996 and 2013 were reviewed. Data regarding the coexistence of dysplastic changes or malignancy within the resected tissues were also retrieved. After the exclusion of malignant cases and patients who were lost for follow-up, 92 patients were included in the study. Five patients had coexisting cellular dysplasia (4.7%), four of them had severe dysplasia and one had mild-to-moderate dysplasia. All four cases with severe dysplasia recurred, three were primarily treated endoscopically and one by external approach. Only the case with mild to moderate dysplasia which had been treated by subcranial approach did not recur. Patients with dysplasia had significantly higher recurrence rate than patients without dysplasia (80 vs. 14%, p = 0.019). This significant relation between histology and recurrence remained even after adjustment to tumor extent. The adjusted odd ratio of dysplasia (dysplasia vs. no dysplasia) is 9.7, p = 0.043. SNIP with dysplasia should be treated aggressively and followed closely. The histopathologic investigation of SNIP specimens should always note the presence of dysplasia and its severity. Further investigation on the clinical behavior of SNIP with dysplasia is needed. Multicenter studies are warranted due to the rarity of dysplastic SNIP.
Keywords: Dysplasia; Inverted papilloma; Malignant transformation; Nasal cavity; Paranasal sinus neoplasms; Paranasal sinuses; Recurrence.