An Unusual Case of Progressive Multifocal Leukoencephalopathy in an Immunocompetent Patient Masquerading as a Stroke

Abstract

Background: Progressive multifocal leukoencephalopathy is a fatal demyelinating condition due to reactivation of latent JC virus in cerebral white matter. Its prevalence is 1in 200,000 and extremely rare in immunocompetent individuals. It can mimic subacute stroke, brain tumours and other demyelinating conditions which have different outcomes. PML typically occurs in an immunocompromised patient, where the archetype JC virus gains pathogenic potential and initiate oligodendroglial inflammation. Currently, the immune reconstitution is considered as the treatment of choice; however, paradoxical worsening with IRIS PML is a significant challenge. There is limited evidence available on how to manage PML in immune competent patients. Direct antiviral agents have no convincing evidence to-date. There is anecdotal evidence that IL-2, filgrastim, and vaccination may be helpful. Case presentation: A 74-year-old man presented with right-sided weakness and dysphasia. He was initially managed as having subacute stroke based on imaging and clinical findings. He subsequently deteriorated, triggering to revisit of the original diagnosis and repeat imaging. He underwent extensive workup, including lumbar puncture and JC viral testing. He was commenced on Mirtazapine to prevent JC viral spread; however, he later passed away. A subsequent post-mortem brain biopsy confirmed the progressive leukoencephalopathy. Conclusion: Even though extremely rare, progressive multifocal leukoencephalopathy should be considered in the differential diagnosis of progressive neurological conditions. It is essential to rule out other treatable conditions as progressive multifocal leukoencephalopathy has a fatal outcome invariably.