Diagnosis:
Clinical features plus MRI and evidence of JC virus infection
Clinical features:
ataxia
Findings on Investigations:
MRI:
- Cerebellar atrophy with or without features of PML
CSF:
- JC virus positive
Pathology, biopsy:
Cerebellum: focal Internal granule cell layer loss, some enlarged granule cell neurons
Special studies:
- Immunohistochemistry for polyomavirus: positive
- In situ hybridization ISH for JCV DNA