- Extra-axial soft tissue mass occupying and enlarging the fourth ventricle.
- It appears isointense on T1 and hyperintense on T2-weighted images with cystic areas.
- It is splaying both cerebellar peduncles and causing scalloping of the posterior aspect of the brainstem and compressing the pre-pontine cistern with minimal extension through foramina of Magendie and left foramen of Luschka.
- Obstructive hydrocephalus is also seen which is likely a chronic process as there is no transependymal CSF spread.
- Heterogeneous, but vivid, enhancement with no diffusion restriction.