Aneurysmal bone cysts (ABCs) are uncommon non-neoplastic, hemorrhagic, and expansile osseous lesions. These lesions most commonly occur in the first two decades of life and affect the long bones and spinal column. Skull base involvement is rare. The authors report the case of a 16-year-old boy who presented with acute visual decline and was found to have a large skull base ABC centered in the sphenoid sinus. In addition, the patient had extensive cranial fibrous dysplasia. The patient underwent a staged expanded endonasal endoscopic approach for complete resection of this lesion with excellent return of his vision. This case adds to the growing body of evidence supporting a role for expanded endonasal endoscopic procedures in pediatric patients with skull base pathologies.