Aneurysmal bone cysts are vascular lesions that destroy and expand bone. We report a recently treated case of an aneurysmal cyst of the sphenoid bone. A 14-year-old girl presented with frontal headaches, bouts of nausea, and vomiting. Computed tomography and magnetic resonance imaging showed typical features of an aneurysmal bone cyst. Arterial embolization was undertaken before surgery. The endoscopic transnasal procedure used allowed the complete removal of the aneurysmal bone cyst. This use of minimally invasive surgery makes this case of interest to surgeons of the skull base and sinuses.

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A 34-YEAR-OLD woman presented in August 1999 with an 8-month history of otalgia and hearing loss in the right ear. On otoscopy, a red mass was found in the hypotympanum, behind an intact tympanic membrane. Hearing tests showed mild conductive hearing loss. The results of neurologic assessment were normal. Subsequent magnetic resonance images (MRIs) and computed tomograms (CTs) demonstrated a lytic tumor of the temporal bone. On CTs (Figure 1 and Figure 2), the tumor seemed to originate from the posteromedial part of the temporal bone. It involved the retrolabyrinthine and infralabyrinthine petrous bone and extended between the internal acoustic meatus and the sigmoid sinus, toward the internal carotid artery forward, the jugular gulf downward, and the hypotympanum laterally. The tumor appeared as a heterogeneous lesion displaying high signal intensity on T2-weighted MRIs (Figure 3). It extended toward the posterior fossa. A small signal was found in the cerebellum (Figure 4). After endovascular embolization of the tumor, a translabyrinthine approach combined with a subtotal petrosectomy was performed in February 2000. The lesion was both extradural and intradural. It appeared as a hypervascular soft tissue mass, filling the mastoid cavity and extending toward the middle ear, hypotympanum, vertical portion of the carotid artery, and lateral sinus, coming into contact with the mastoid portion of the facial nerve. Dura of the posterior fossa was invaded, and a small mass (about 1 cm) was found in the posterior fossa. The tumor was totally removed. Pathologically, it showed a typical papillary architecture. Immunohistochemical stains were positive for cytokeratin, epithelial membrane antigen, vimentin, S100 protein, and neuron-specific enolase.Aftersurgery,afullradiologicevaluationwasperformed. The MRIs of the abdomen revealed pancreatic cysts. No abnormalities were found on ophthalmologic assessment or on MRIs of the spinal cord. The results of measurement of 24-hour urinary metanephrin excretion were negative. A 15-month follow-up period has been uneventful.