Progressive multifocal leukoencephalopathy is caused by reactivation of the polyomavirus JC, affecting the white matter of the central nervous system. We present a rare case of JC virus granule cell neuronopathy (JCV GCN) in PML mimicking miller fisher syndrome (MFS) in an AIDS patient.

A 55-year-old African American male with a history of untreated HIV presented with bilateral lower extremity weakness, ataxia, and diplopia for 3 weeks. His initial examination showed muscle weakness in the upper and lower limbs, diplopia, ataxia, and areflexia. CSF analysis showed albuminocytologic dissociation and a negative meningitis panel. Electrodiagnostic studies showed a sensorimotor mixed polyneuropathy. Serum GQ1B antibody, CSF oligoclonal bands and IGG index were positive. He was diagnosed with MFS, received a course of IVIG with clinical improvement. He was discharged on HAART therapy.

He presented 2 months later with worsening symptoms. His CD4 count increased from 50 to 200. Brain MRI showed a faintly enhancing T2 hyperintense lesion involving the cerebellum and brainstem. Repeat LP showed elevated protein and WBC, as well as EBV positivity on PCR and monoclonal B cells on flow cytometry. He was then started on steroids, with marginal improvement. Repeat imaging showed rapid expansion of the previously shown lesion. MR spectroscopy favored an infectious/demyelinating process. Brain stereotactic biopsy was positive for JCV and demonstrated PML as well as B-Cell Clonality. Oncology deemed the B-Cell Clonality nonconfirmative in the setting of PML.

PML is a severe demyelinating disease of the CNS. JCV GCN in PML could lead to atypical clinical presentation mimicking MFS. The positive serum GQ1B antibody and CSF OCBs in this case have contributed to the clinical decision-making process leading to the final diagnosis. Additional studies are needed to see whether these biomarkers could be utilized in clinical practice to differentiate PML from CNS lymphoma.