Progressive multifocal leukoencephalopathy in idiopathic CD4+ lymphocytopenia.

Progressive multifocal leukoencephalopathy is a central nervous system demyelinating disease caused by infection with John Cunningham virus. It affects predominantly the subcortical white matter, producing progressive neurological deficits and large confluent white matter lesions on imaging. It is usually seen in immunodeficient individuals, such as those suffering from acquired immunodeficiency syndrome, those on treatment with monoclonal antibodies, and those following therapeutic bone marrow suppression. Here, we report a rare case of progressive multifocal leukoencephalopathy in an apparently immunocompetent adult, who was found to have idiopathic CD4 lymphocytopenia upon further investigation.