Progressive multifocal leukoencephalopathy (PML) is a rare demyelinating disease of the central nervous system caused by reactivation of John Cunningham (JC) virus. Risk factors for the development of PML include infection with human immunodeficiency virus (HIV) or treatment with immunosuppressive therapy. This latter group, termed drug-associated PML, has been linked to rituximab, fludarabine, and brentuximab;...Continue Reading