<unk>  <unk>  is a rare, demyelinating CNS disorder
Associated with reactivated JC virus
Seen almost exclusively in immunosuppressed patients, usually due to:
AIDS
Leukemia, lymphoma, myeloproliferative disorders (with or without chemo)
Post solid organ or stem cell transplant
Autoimmune disorders (with or without immune-modulating medications)
Medications: Natalizumab, rituximab, infliximab, mycophenolate mofetil
AIDS
Leukemia, lymphoma, myeloproliferative disorders (with or without chemo)
Post solid organ or stem cell transplant
Autoimmune disorders (with or without immune-modulating medications)
Medications: Natalizumab, rituximab, infliximab, mycophenolate mofetil
Progressive multifocal leukoencephalopathy
Hypoxic encephalopathy
Primary CNS lymphoma
Acute toxic-metabolic encephalopathy 
Drug induced aseptic meningitis
Hypoglycemia
Japanese encephalitis
Hyperosmolar state 