Calcified epithelial odontogenic tumor (CEOT) with extension to the maxillary, ethmoid and sphenoid sinuses is currently unreported. This extension poses a challenge for effective treatment, as CEOT is a benign neoplasm with contreversial potential aggressiveness. We report a case of CEOT that was previously misdiagnosed as an inverted papilloma. A segmental resection of the part of the tumor responsible for the symptoms was performed. Histology revealed polyhedral epithelial cells within an amorphous eosinophilic hyaline material containing round calcified structures and confirmed the diagnosis of CEOT. Postoperative CT Scan showed the partial resection of the tumoral process. A mixed radiolucent/radiopaque aspect of the remaining CEOT was clearly discernible. The patient was warned that due to the incomplete excision of the tumoral process, the risk of recurrence was significant and that a close clinical and radiological follow-up every 6 months was mandatory for a long time.