An adult patient with initial presentation of myxopapillary ependymoma at the cerebellopontine angle: illustrative case.

Background: Myxopapillary ependymomas (MPEs) are a relatively rare subtype of ependymoma that occur almost exclusively at the conus medullaris and filum terminale in the lumbosacral spine. Intracranial occurrences of this tumor are rare, and of those, localization to the cerebellopontine angle (CPA) is an exceptional event. To the authors' knowledge, this is the fifthreported MPE in the CPA and only the third reported instance of an MPE in the CPA at the initial presentation.

Observations: The authors describe an adult patient with an initial presentation of MPE at the CPA, originally thought to be a schwannoma on radiological imaging. Follow-up imaging later revealed additional clinically asymptomatic spinal masses consistent with MPEs. This case is particularly unique not only because of the patient's presenting symptoms being exclusive to tinnitus and ear fullness without any spinal symptoms, but also because it is the first case, to the authors' knowledge, in which DNA methylation profiling results have been reported to confirm the diagnosis of MPE in the CPA.

Lessons: This case highlights the importance of considering a broad differential diagnosis for lesions in the CPA. https://thejns.org/doi/10.3171/CASE2586.