Progressive multifocal leukoencephalopathy: immunofluorescent demonstration of simian virus 40 antigen in CSF cells and response to cytarabine therapy.

We report an instance of progressive multifocal leukoencephalopathy in which cytarabine administration was successful as demonstrated by clinical course and follow-up computerized tomography studies. In this case, simian virus 40 (SV40) antigen was demonstrated in CSF cells by the indirect immunofluorescence technique.