J Korean Soc Radiol.  2013 Apr;68(4):281-284. 10.3348/jksr.2013.68.4.281.

The CT and Magnetic Resonance Imaging Features of Transotic Schwannoma: A Case Report

• Lee SK
• Choe MS

• KMID: 1425142
• DOI: http://doi.org/10.3348/jksr.2013.68.4.281

Abstract

Transotic schwannoma is a condition extremely rare, and we herein report the CT, MRI, and pathologic findings of a transotic schwannoma case in a 38-year-old woman. The lesion was identified as an expansile mass in the internal auditory canal (IAC) and a mass in the middle ear cavity (MEC) on the high-resolution, bone algorithm, temporal bone CT. It was shown as the following: the hypointense masses of the cerebellopontine angle (CPA)-IAC and MEC, and the hypointense replacement of the normal high-signal intensity fluid of the cochlea, vestibule, and semicircular canals on the 3-dimensional (3D) fast imaging, employing the steady-state acquisition (FIESTA) sequence; and the intensely enhancing masses of the CPA-IAC and MEC, and the intense enhancement of the cochlea, vestibule, and semicircular canals on the 3D gadolinium-enhanced spoiled gradient-recalled echo (SPGR) sequence. The mass was removed via a transotic approach. The pathologic findings were consistent with schwannoma. The assessment of the extent of transotic schwannoma may be enhanced by the 3D FIESTA and the gadolinium-enhanced SPGR sequences.

MeSH Terms

Cerebellopontine Angle
Cochlea
Ear, Middle
Female
Humans
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Magnetics
Magnets
Neurilemmoma
Semicircular Canals
Temporal Bone
Tomography, X-Ray Computed

Figure

• 

  Fig. 1 CT, MRI, and pathologic features of transotic schwannoma in a 38-year-old woman. A. A coronal high-resolution temporal bone CT image shows an expansile mass in the left internal auditory canal (IAC) (white arrow), and a mass in the left middle ear cavity (MEC) (black arrow) extending from the inner ear through the oval window (arrowhead). B. An axial 3-dimensional (3D) fast imaging employing the steady-state acquisition (FIESTA) image reveals a hypointense mass in the left cerebellopontine angle (CPA)-IAC (black arrow), and hypointense replacement of normal high signal intensity fluid of the left lateral semicircular canal (arrowhead). Note normal high signal intensity of the right superior and posterior semicircular canals (white arrows). C. A gadolinium (Gd)-enhanced axial 3D spoiled gradient-recalled echo (SPGR) image demonstrates heterogeneous, intensely enhancing mass (arrow) in the left CPA-IAC, and intense enhancement of the left lateral semicircular canal (arrowhead). D. A Gd-enhanced axial 3D SPGR image shows an enhancing mass in the left MEC (white arrow) extending from the inner ear through the round window (black arrow). Also noted is intense enhancement of the left cochlea (arrowhead). E. A Gd-enhanced coronal 3D SPGR image shows the components of transotic schwannoma consisting of a dumbbell-shaped mass of the left CPA (arrow 1)-IAC (arrow 2), intense enhancement of membranous labyrinth (arrow 3), and a mass in the MEC (arrow 4) extending from the inner ear through the oval window (arrowhead). F, G. A photomicrograph of histological examination (F) of the specimen obtained by surgical resection demonstrates proliferation of the spindle cells in short bundles and nuclear palisading (arrowheads) (hematoxylin-eosin, × 200), and a photomicrograph of immunohistochemical staining (G) reveals strong positivity for S-100 protein in the cytoplasm and nuclei of tumor cells (original magnification, × 200), which are consistent with schwannoma.

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