Giant Ossifying Fibroma of the Ethmoid Sinus, Orbit, and Anterior Skull Base: Endoscopic Endonasal Approach

Introduction: Ossifying fibroma (OF) is a benign fibro-bone tumor that affects the bones of the face, but rarely involves the ethmoid sinus and orbit. The lesion is asymptomatic in most cases until growth produces facial deformity.

Case Report: A 45-year-old previously healthy woman presented to the emergency department complaining of headache and nasal discharge, evolving with ocular proptosis, pain and right periorbital edema. CT scans demonstrated a lesion centered on the skull base and ethmoid sinus, with involvement of drainage pathways and right orbit. The patient underwent endoscopic endonasal skull base surgery for tumor removal. Surgery was uneventful and patient was dismissed from hospital on the fifth postoperative day. Pathology confirmed a cementoossifying fibroma.

Discussion: OF are fibroosseous lesions that mainly involve facial bones and usually present with a slightly exuberant clinical picture. However, as tumor growth advances, facial asymmetry and neurological symptoms may occur due to compression of vital structures. In the reported case, there was visual field impairment and oculomotor nerve palsy due to extrinsic cranial nerve compression. Endoscopic endonasal surgery was effective to remove the tumor offering a straightforward approach.

Conclusion: Although a benign tumor, in this case the OF presented as an aggressive lesion due to the extension of the mass and compression of adjacent structures. Endoscopic endonasal approach for ossifying fibromas has proved to be an excellent therapeutic option, providing direct visualization and the absence of facial scars.