Presentation
Incidental finding on a CT Brain performed for other reasons.
Patient Data
There is an ill-defined hypodense right cerebellar hemisphere mass that does not enhance and does not cause significant mass effect over the posterior fossa structures. It appears to spare and distort the cortex of the cerebellar folia. The remainder of the brain has normal appearances. MRI Brain is recommended for further characterization of the lesion.
There is a mass like focal lesion involving the superior and lateral aspect of the right cerebellar hemisphere and characterized by widening and anatomical distortion of the cerebellar folia with a striated cystic appearance. It does not show enhancement or diffusion restriction. Spectroscopy traces are unremarkable, similar to the contralateral cerebellar hemisphere. There is a local mass effect with an herniated right cerebellar tonsil descending about 7 mm below the foramen magnum and mild distortion of the fourth ventricle. No hydrocephalus. The remainder of the brain parenchyma appears normal.
Case Discussion
This patient has a right hemisphere cerebellar mass-like lesion that is highly suggestive of Lhermitte-Duclos disease and imaging follow-up has been considered for now. Follow-up at 6 weeks showed no change.
Other differentials such as nodular medulloblastoma can have a similar morphology but would be expected to have more pronounced cortical expansion and contrast enhancement, both absent in this case.
Special thanks to Dr Christine Goh and A/Prof Frank Gaillard, also involved in this case clinical discussion.
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