Presentation
Right trigeminal neuralgia
Patient Data
The MRI sequences demonstrate an extra-axial lobulated mass at the right cerebellopontine angle (CPA), extending to the prepontine/ambient/interpeduncular cisterns as well as the ipsilateral Meckel's cave, compressing the brainstem, midbrain, and ipsilateral trigeminal nerve, and middle cerebellar peduncle. There is also an extension into the ipsilateral IAC well-visualized on axial Fiesta sequence with encasement of the basilar artery. It shows a low signal on T1WI, heterogeneous signal on FLAIR and high signal on T2WI with restricted diffusion on DWI/ADC. No enhancement seen on postcontrast sequences.
Case Discussion
MRI features characteristic of an epidermoid cyst of the cerebellopontine angle , compressing the trigeminal nerve.
DWI is important to differentiate an epidermoid cyst from an arachnoid cyst.