Stroke Mimics: A Case of John Cunningham Virus-Induced Progressive Multifocal Leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is a rare, often fatal neurological disorder caused by the John Cunningham virus (JCV). It affects immunocompromised individuals, leading to brain demyelination. Diagnosis involves MRI scans and JCV detection in cerebrospinal (CSF) fluid. The mortality rate is high, and current intervention focusses on reversing immunosuppression. We report a patient with chronic lymphocytic leukaemia (CLL) who was diagnosed with PML. He is a 66-year-old male with CLL presenting with multiple falls, right arm weakness, and cognitive impairment. Following MRI head scans and CSF analysis, he was diagnosed with PML. Treatment for CLL was deemed inappropriate due to immunosuppression risk. We initiated Levetiracetam to prevent seizures and considered mirtazapine to prevent viral spread. Mefloquine and cidofovir were considered, but the patient chose not to commence on them. He was discharged with multidisciplinary support. In conclusion, we advise that these stroke-like symptoms may necessitate comprehensive investigation beyond initial CT scans, as exemplified by this case of PML. Relying solely on radiological findings may overlook rare conditions, and clinical skills such as a good history and examination should still be prioritised.