Findings
Midline structures are within normal limits. The ventricular size, shape and configuration are within normal limits and unchanged. There is a partially empty sella. There is no evidence of vasogenic edema or mass effect. The contrast-enhanced T1-weighted images show no abnormal intraaxial enhancing masses. Incidental note is made of partial pneumatization of both mastoid air cells. Diffusion-weighted imaging shows no evidence of recent infarct. Gradient-echo imaging shows no evidence of hemosiderin staining.
Internal Auditory Canal: Thin-section imaging performed through the internal auditory canal shows a heterogeneous mass involving the left cerebellopontine angle. The mass has a frond-like appearance which is best appreciated on the heavily T2-weighted images. The mass can be detected on the T2-weighted images but has greater conspicuity on the FLAIR sequences.
The lesion is centered just lateral to the left porous acusticus and directly abuts the cisternal segment of the left 7th and 8th nerve complex. The superior component of the mass abuts the lateral aspect of the left cisternal segment of the trigeminal nerve. The inferior component extends just inferior to the cisternal segment of the 7th and 8th nerve complex. There is no appreciable enhancement. The lesion is high signal on diffusion-weighted imaging. Mild mucosal thickening involving the anterior aspect of the left mastoid air cells.
Conclusions
1. Findings are most consistent with epidermoid tumor of the left cerebellopontine angle.
2. No evidence of vasogenic edema or mass effect.
3. No abnormal intraaxial or extraaxial enhancing masses.