Presentation
Ataxia, gait disturbance, and vertigo for a few weeks.
Patient Data
Large solid mass located centrally within the posterior fossa with mild vasogenic edema. It is high T2 signal and low T1 signal with marked water restriction on DWI images
No normal vermis can be identified and the mass is likely to arise from it
Minimal pressure effect on the fourth ventricle
Another similar smaller mass at the right cerebellar hemisphere superior part shows water restriction on DWI images.
Post-treatment changes as:
Diffuse pachymeningeal enhancement
Malacic changes surrounded by gliosis and hemosiderin rim along the cerebellar vermis and right cerebellar hemisphere
Two abnormal signal areas ( high on T1 and iso signal on T2 ) at the right cerebellar hemisphere and cerebellar vermis due to hematoma on subacute phase
Right lateral ventricle VP shunt
A few high signal foci in T2 and flair sequences at subcortical and periventricular white matter of both cerebral hemispheres depict microvascular ischemic events.
Desmoplastic/nodular medulloblastoma, WHO grade IV.
Case Discussion
The imaging features are typical of medulloblastoma with high cellularity accounting for diffusion restriction. The diagnosis was confirmed histologically.