Combined Endoscopic and Open Approaches for Sinonasal and Skull Base Aneurysmal Bone Cyst: A Case Report

Introduction: An aneurysmal Bone Cyst (ABC) is a vascular tumor believed to be attributable to vascular occlusion and congestion causing intraosseous circulatory disturbance that prompts bony expansion and dysplasia. ABCs most commonly occur in the metaphysis of long bones. Craniofacial ABCs account for <1%, orbital involvement is implicated in 0.25%, and very scarce data exists on ethmoidal, sphenoid, or frontal sinus and skull base infiltration.

Methods and Results: The authors report the case of a 7-year-old female who presented with a 1-month history of painless proptosis; sudden decrease in vision; increased lacrimation; bilateral nasal obstruction; white nasal discharge; and mild frontal headache. Her visual acuity was 20/200 in the right eye and counting fingers near her face in the left eye, and she exhibited a +3 (immediate pupillary dilatation) afferent pupillary defect in the left eye. Otolaryngology examination revealed bilateral nasal obstruction. Preoperative imaging revealed a hyperdense multiloculated bony lytic lesion centered in the nasal cavity and ethmoidal sinus with extension posteriorly to the anterior cranial fossa causing frontal skull base erosion; and laterally to the roof of the right orbit causing displacement of the orbit and compressing bilateral optic nerves. The large lesion was resected via a multidisciplinary combined endoscopic endonasal approach and a bifrontal craniotomy in the same setting to achieve gross total resection (GTR) and decompress the optic nerves bilaterally. Pathology revealed regular variably blood-filled cystic spaces with walls composed of fibroblasts, hemosiderin, and giant cells, consistent with the diagnosis of an aneurysmal bone cyst. The patient remained under close observation with resolution of symptoms and significant improvement of her exophthalmos from the immediate postoperative period until last follow-up one year postoperatively, without complications. In this case, we aimed to illustrate the clinical and radiological results of a same sitting combined approach for a large lesion compressing vital structures and to review the literature on similar approaches and their outcomes. GTR followed by bone grafting is the treatment of choice and familiarity with skull base techniques is imperative for managing these scarcely encountered lesions.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
05 February 2024