Abstract

Aneurysmal bone cyst (ABC) is benign vascular lesion destructing the cortical bone by the expansion of the vascular channel in the diploic space that usually involve long bone and spine. Orbital ABC is rare and the clinical symptoms deteriorate rapidly after initial slow-progression period for a few months. A 12-year-old female patient visited ophthalmologist due to proptosis and upward gaze limitation of the right eye, and orbital mass was noted in the upper part of right eye on orbital MRI. Five months later, exophthalmos was worsened rapidly with other features of ophthalmoplegia. Orbital mass was enlarged on MRI with intracranial extension. Surgery was done through frontal craniotomy and intracranial portion of the tumor was removed. Destructed orbital roof and mass in the orbit was also removed, and surrounding bone which was suspected to have lesion was resected as much as possible. Histopathological diagnosis was aneurysmal bone cyst. Postoperative course was satisfactory and the patient's eye symptoms improved. Authors report a rare case of orbital ABC with review of the literature. Exact diagnosis by imaging studies is important and it is recommended to perform surgical resection before rapid-progressing period and to resect the mass completely to prevent recurrence.