ABSTRACT
Progressive multifocal leukoencephalopathy (PML) is a progressive lethal demyelinating disease of the brain, caused by JC virus. Reactivation of JC virus due to reduction of cellular immunity especially in setting of AIDS, is the commonest underlying cause. PML has classically been described in individuals with profound cellular immunosuppression such as patients with AIDS, haematological malignancies, organ transplant recipients or those treated with immunosuppressive or immunomodulatory medications for autoimmune diseases. Rarely it has also been diagnosed in cases with no or minimal immunosuppression. Here, we report a 50 year-old man who presented with sudden onset multiple neurologic defi cits. Neuroimaging, histopathology, and virology studies confi rmed the diagnosis of PML. We could not however demonstrate any underlying immunodefi ciency state. Our case suggests that absence of immunodefi ciency does not exclude the possibility of PML and should be considered in immunocompetent patients with a typical clinical course and neuroimaging fi ndings.