Sinonasal papillomas: Clinicopathologic review of 40 patients with inverted and oncocytic schneiderian papillomas

Objective: To evaluate the pathological features and variations of sinonasal inverted and oncocytic papillomas and correlate the microscopic findings with the clinical behavior. Study Design: A retrospective review and pathological assessment. Methods: A retrospective review and pathological assessment were performed on 40 patients with a diagnosis of inverted papilloma treated by the senior author (W.L.) between 1994 and 2001. Results: Forty cases were identified and reviewed. Seven patients developed recurrences (18%), and four underwent malignant transformations (10%). Pathological assessment revealed 34 (85%) inverted papillomas and 6 (15%) oncocytic schneiderian papillomas. Dysplasia was present in 26 cases (65%), including 9 cases (22%) of high-grade dysplasia (moderate to severe). Metaplasia of the sinonasal mucosa adjacent to inverted papillomas and oncocytic schneiderian papillomas was seen in 18 (45%) cases. Recurrence developed in two patients with oncocytic schneiderian papillomas (33%) and five patients with inverted papillomas (15%). Four cases (10%) of carcinoma ex papilloma were seen; one arose from oncocytic schneiderian papilloma (17%), and three arose from inverted papilloma (9%). Oncocytic schneiderian papilloma was more often mixed with typical inverted papilloma, rather than presenting in its pure form. Conclusions: Although oncocytic schneiderian papilloma is uncommon relative to inverted papilloma, the results suggest that they have higher rates of both recurrence and malignant transformation. The common admixture of oncocytic schneiderian papilloma with inverted papilloma speaks for a common etiological factor of these two lesions. A larger number of cases for analysis would be necessary to confirm the trend noted in our data. Nonetheless, pathological findings consistent with oncocytic schneiderian papilloma should be explicit in any classification system and justify aggressive treatment and careful postoperative surveillance.