Objective: To determine by review of their histogenesis whether papillomas of the nose and paranasal sinuses are three distinct entities or, as has been favored in the literature, three variations of a single entity.
Methods and patients: We examined biopsy sections from 191 patients with sinonasal papillomas. Biopsy sections included all types of sinonasal papillomas stained using routine methods and, in some cases, using immunohistochemistry for macrophages (PG-M1) and proliferation antigen (MIB-1). Two cases of inverted papilloma were also examined using transmission electron microscopy.
Results: Everted and cylindric cell papillomas are true papillomas, lined by stratified squamous and microcystladen, columnar, oncocytic epithelium, respectively. Inverted papillomas are polyps with marked, patchy squamous metaplasia and numerous microcysts containing macrophages in ductal and surface epithelium. There are no intermediate forms from any one of the three types to another.
Conclusions: Some differences between the three types are already established with regard to sites of origin, tendency to recur, and association with malignancy. It is likely that their etiologies--eg, concerning human papillomavirus infection--will be found to differ, if their distinct histogeneses are considered.