The patient went on to have a biopsy.

Histology

Sections of cerebellum show enlarged, architecturally distorted folia. There is diffuse enlargement of the molecular and internal granular layers expanded by a population of ganglion cells. The outer molecular layer contains abnormal bundles of myelinated axons. There are focal deposits of dystrophic calcification present. The dysmorphic ganglion cells contain abundant amphophilic cytoplasm, oval vesicular nuclei and prominent nucleoli. No necrosis or microvascular proliferation is seen. There is no evidence of malignancy.

FINAL DIAGNOSIS: dysplastic cerebellar gangliocytoma (Lhermitte Duclos disease) - WHO Grade I.