Intraaxial mass-like lesion is demonstrated in the left cerebellar hemisphere and vermis. It is heterogeneously high-signal on T2-weighted imaging, with a striated appearance. There are multiple flow voids related to the lesion, although most appear to be at the peripheries and may be adjacent or in compressed sulci. On postcontrast T1-weighted imaging, there is only enhancement of vessels with no convincing enhancement of the lesion. No associated cystic component. MRS is unremarkable (not shown).
The mass distorts the fourth ventricle, compressing the foramina of Magendie and Luschka with resultant hydrocephalus. The mass also expands the left cerebellar hemisphere, with descent of the left cerebellar tonsil 10 mm below the foramen magnum.
No other intracranial lesion. No collection or acute haemorrhage. No cortical infarct.
Conclusion: Features are those of a dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease).