Posterior Fossa Ependymoma: Unusual Extension into the Internal Auditory Canal in a 32-year-old Woman

Ependymomas are relatively rare glial neoplasms that arise from ependymal cells. The majority of cases (>75%) arise from the fourth ventricle in the posterior fossa. These tumours may expand locally, extend along subarachnoid spaces, and disseminate through the cerebrospinal fluid. Sometimes, they may extend into the cerebellopontine angle and mimic the clinicoradiological appearance of an extra-axial lesion. However, it is extremely unusual for such a lesion to extend into the internal auditory canal and mimic an acoustic neuroma. Such an unusual occurrence of a fourth ventricular ependymoma that extended into the right internal auditory canal through the porus acousticus is described in this case report. Also discussed are the imaging characteristics that could help distinguish between extra-axial lesions of the cerebellopontine angle and exophytic brain tumours.