Extradural dermoid cyst of the parasellar region: a case report

Abstract

Dermoid cysts are rare congenital intracranial tumors. Among these tumors, extradural localization is extremely rare. We report a patient with an extradural dermoid cyst of the right parasellar region, causing right visual disturbance. Computed tomography revealed a hypodense mass lesion with rimlike calcification at the right parasellar region, accompanying marked erosion of the adjacent skull base. The tumor appeared as a heterogeneous intensity on magnetic resonance imaging and was surrounded by thin gadolinium enhancement without inner enhancement. The right optic nerve was compressed by the tumor. Surgical resection was successfully performed using a right frontotemporal extradural approach. The entire tumor was completely resided extradurally and was enclosed by saclike, stretched dura mater and extended deeply into the skull base. Histopathologic findings were consistent with the features of dermoid cyst. The postoperative course was uneventful, and the visual disturbance improved. Neuroradiological features, strategies for surgical treatment, and mechanisms responsible for preoperative symptoms are discussed.

Keywords: Intracranial dermoid cyst; extradural localization; parasellar region; surgical treatment.

Figure 1

Radiological findings on initial presentation. Computed tomography (CT) showing the tumor as a hypodensity with rimlike calcification at the right parasellar region (A). Three-dimensional CT angiography demonstrating the skull base erosion and the compressed intracranial major vessels (B). Axial T1- (C) and T2-weighted magnetic resonance imaging (MRI) (D) demonstrating a heterogeneous mass lesion. Diffusion-weighted image showing the tumor as marked hyperintensity (E). Axial (F) and coronal (G) fat-suppression T1-weighted MRI with gadolinium enhancement revealing thin enhancement of the tumor rim, which continued to the dura mater.

Figure 2

Intraoperative view. (A) The extradural tumor (black asterisk) enclosed by saclike, stretched dura. Black arrowhead and white arrowhead showing the lateral wall of the right cavernous sinus and meningo-orbital band, respectively. (B) Right optic nerve (black arrow) revealed via eroded optic canal and optic nerve sheath. (C) Intradural inspection. Firm adhesion between right M1 and inner surface of thickened dura mater. (D) No intradural tumor observed through right sylvian fissure.

Figure 3

Postoperative axial T1-weighted magnetic resonance imaging (MRI) with gadolinium enhancement (A), T2-weighted MRI (B), and coronal T1-weighted MRI with gadolinium enhancement (C) 3 months after surgery showing no residual tumor.