Progressive multifocal leukoencephalopathy limited to the posterior fossa

Progressive multifocal leukoencephalopathy (PML) is a rapidly progressive demyelinating disease caused by the reactivation of JC papova virus usually in immunocompromised hosts.1 The disease is a chronic viral infection resulting in mortality within a year.2 The condition characterized by white matter changes in multiple locations of the brain is caused by destruction of the oligodendrogliocytes.2 We report a case of AIDS associated PML presenting with progressive cerebellar symptoms, with the unusual feature of imaging abnormalities limited to the posterior fossa.