Endoscopic Removal of Sinonasal Inverted Papilloma Originating From the Posterior Ethmoid Cavity.

Sinonasal inverted papilloma is an expansive, benign mass derived from the Schneiderian membrane. It may undergo malignant transformation and most commonly originates from the maxillary sinuses or the lateral walls of the nasal corridors. This case outlines the case of a sinonasal inverted papilloma, which clearly arises from the posterior ethmoid sinus, bordering the skull base.