Trans-Ethmoidal Endoscopic Resection of a Giant Orbital Osteoma: Technical Considerations

Introduction: Osteomas are the most common paranasal sinus tumor. Orbital osteomas, however, are extremely rare and often require an open surgical approach especially in cases of large tumors. We present the unique case of an unusual giant orbital osteoma removed by an entirely endoscopic approach.

Case: The patient was a 20-year-old white female who works as a model presenting with mild left eye protrusion. On exam extraocular movements were intact, pupils were equal and reactive, and visual acuity was unaffected. There was noticeable left eye protrusion on exam. Review of MRI showed a calcified neoplasm of the anterior cranial skull base and left orbit with proptosis. We recommended a nontraditional approach to resecting the tumor. Classic recommendation would be to perform a craniotomy and orbitocranial osteotomies to resect this large osteoma; however, we felt that a transnasal endoscopic approach would be successful and give better aesthetic outcomes for this patient. We performed a modified anterior craniofacial approach to this tumor of the skull base, including extended radical endoscopic ethmoidectomy, medial maxillectomy, and resection of middle turbinate. Intraoperatively, the tumor was noted to be a very unusual with heavy calcification originating from the anterior cranial base including the roof of the ethmoid and cribriform plate, and attaching broadly to the skull base, medial and inferior orbital walls, and the medial maxilla. This tumor also had a predominant lobulated projectile protruding medially into the orbit almost to the opposite lateral wall. This projection occupied so much of the posterior orbit that much greater clinical deficits would have been expected. Ultimately this unusual tumor was so large and calcified it was unable to be either removed transnasally or transected into smaller pieces. Consequently, we performed a posterior nasal septectomy to deliver the tumor transorally.

Conclusion: This unusual tumor presented an interesting operative challenge. We were able to successfully remove this giant osteoma of the orbit completely endoscopically allowing excellent cosmetic results for a patient who works as a model. Her proptosis was improved immediately post-operatively and there were no visual deficits or impaired movement of the orbit.