Oncocytic Schneiderian papilloma.

Oncocytic Schneiderian papilloma, fungiform papilloma, and inverted papilloma are 3 morphologically separate tumors arising from the Schneiderian membrane. Oncocytic Schneiderian papillomas comprise about 3 approximately 5% of this entity. Old-aged group predominates. No sex predilection is noted. Multi-layered eosinophilic epithelium characterizes this kind of tumor. Exophytic and inverted growth pattern is found microscopically. It is often confused with sinonasal adenocarcinomas which contain only single-layered epithelium. Clinically, its behavior parallels inverted papillomas due to local recurrence and coexistence of malignancy. We reported a case of oncocytic Schneiderian papilloma arising from the anterior ethmoid sinus and extending to maxillary sinus antrum. Although destruction of the lamina papyracea was noted preoperatively, no malignancy was found microscopically. We adopted endoscopic approach and removed the tumor thoroughly. External approach was necessary if tumor extent was not feasible to endoscopic approach. The etiology of oncocytic Schneiderian papillomas remains unknown. However, it should be considered in the differential diagnosis of unilateral nasal polypoid lesions clinically.