A 33 year old male presented with homonymous hemianopia. He also has ataxia and personality changes. Characteristic inclusions are seen in oligodendrocytes. What is the MOST probable diagnosis in this patient?

Progressive multifocal leukoencephalopathy(PML) is characterized pathologically by multifocal areas of demyelination of varying size distributed throughout the brain but sparing the spinal cord and optic nerves. Characteristic microscopic feature: 1. Oligodendrocytes have enlarged, densely staining nuclei that contain viral inclusions formed by crystalline arrays of JC virus (JCV) paicles. 2. Astrocytes are enlarged and contain hyperchromatic, deformed, and bizarre nuclei and frequent mitotic figures. Clinical presentation: Visual deficits (45%), typically a homonymous hemianopia Mental impairment (38%) (dementia, confusion, personality change) Weakness, including hemi- or monoparesis Ataxia Ref: Roos K.L., Tyler K.L. (2012). Chapter 381. Meningitis, Encephalitis, Brain Abscess, and Empyema. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.