Temporal bone and sinonasal inverted papilloma - The same pathological entity?

Background: Inverted papilloma involving the temporal bone is an extremely rare occurrence. Reports in the literature suggest a higher recurrence rate and association with squamous cell carcinoma in Schneiderian-type papillomas of the middle ear than in sinonasal Schneiderian-type papillomas. Objectives: To investigate the expression of apoptosis-related proteins, markers of cell proliferation activity, and sex hormone receptors in temporal bone inverted papillomas and to compare this entity with sinonasal papillomas. Design and Subjects: We investigated 2 rare cases of inverted papilloma of the temporal bone and a control group of 6 cases of sinonasal inverted papilloma. The expression of p53, Mib-1, p27, and progesterone and estrogen receptors was determined. Results: In the 2 cases of temporal bone inverted papilloma, p53 expression was 43.75% and 4.92%; p27 expression was higher in temporal bone inverted papilloma (82.45% and 70.53%) than in the sinonasal inverted papilloma group. One of our 2 cases of temporal bone Schneiderian-type papilloma was positive for progesterone receptor. Conclusions: The expression of progesterone receptor in 1 of our 2 cases and in the only other case reported in the literature may imply some degree of hormonal dependence of temporal bone inverted papilloma. Our analysis of the expression of apoptosis-related proteins, markers of cell proliferation activity, and sex hormone receptors does not allow us to demonstrate that temporal bone and sinonasal inverted papilloma are different pathological entities.