PMC3114313_01
CT scan shows an isodense mass in the temporal fossa (a). The bone-window CT scan, with coronal image (b), shows a clear extension into the tympanic cavity; the axial view (c) reveals the erosion of the anterior aspect of the petrous bone (arrows)
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F1
A computed tomography (CT) scan revealed an isodense subtemporal mass, with a partial calcification of the rim and the erosion of the anterior aspect of the petrous bone, with a clear extension into the tympanic cavity [Figure 1].
Pre-operative MR images shows a mass hypo- or isointense relative to the brain on T1-weighted and heterogeneously hyperintense on T2-weighted images with enhanced after administration of gadolinium developing from the facial hiatus to the foramen lacerum of 3.8 x 3.3 x 2.8 cm
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F2
Magnetic resonance imaging (MRI) confirmed the presence of an extradural mass (3.8 x 3.3 x 2.8 cm) in the middle cranial fossa, isointense on T1-weighted images and mildly hyperintense on T2-weighted images, causing a compression and dislocation of the temporal lobe [Figure 2].
Intraoperative image showing the lesion arising from the greater petrosal nerve. GPN: greater petrosal nerve; Pet. B.: petrous bone; Tu: tumor
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F3
The tumor was exposed by a left subtemporal extradural/interdural approach while continuously monitoring facial nerve electromyography; during the mobilization of the postero-inferior portion of the tumor, the GPN was identified [Figure 3].
Post-operative MR images demonstrate the complete removal of the tumor. The tympanic opening was filled with autologous abdominal subcutaneous fat tissue
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F4
Post-operative CT scan and MRI showed the complete resection of the lesion [Figure 4].
Microscopic and immunohistochemical examination showing nuclear hyperchromasia and pleomorphism of the schwannoma (a). The cellularity of the tumor, positive for S-100 (c and d) and Vimentin, is biphasic containing both Antoni A (black arrow) and Antoni B (white arrow) tissue (b)
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F5
The histological evaluation revealed a typical biphasic schwannoma, containing both Antoni A and Antoni B tissue [Figure 5].