Endoscopic Removal of Massive Sinonasal and Skull Base Osteoblastoma

Abstract

Objective: Osteoblastomas are uncommon bone neoplasms, accounting for 1% of all newly diagnosed primary bone tumors. Sinonasal and skull base osteoblastomas are exceedingly rare. We describe an endoscopic resection of a massive sinonasal/skullbase osteoblastoma, which was misdiagnosed as an ossifying fibroma. We discuss the histopathologic diagnosis of these sinonasal bony lesions. Method: Case report and current literature review. Results: A 14-year-old female presented with progressive right-sided proptosis and nasal obstruction. CT and MRI scanning demonstrated a massive sinonasal lesion with orbital and skull base involvement. An endoscopic biopsy performed by another otolaryngologist revealed a fibrous and highly vascular lesion. Histopathologic diagnosis was consistent with an ossifying fibroma. Endoscopic endonasal extended approach of this anterior skull base tumor was successfully performed with complete resection. Final histopathologic diagnosis revealed an osteoblastoma. The patient did well postoperatively without complication. Conclusion: This case aims to increase awareness of this infrequently encountered disease of the nasal cavity and paranasal sinuses and offers insight into the diagnosis and treatment of this rare entity.