Progressive multifocal leukoencephalopathy with a benign prognosis in an immunocompetent patient - A case report.

John Cunningham virus (JCV) is most commonly acquired in childhood and is often asymptomatic throughout life. However, in the case of primary or secondary immunosuppression, it is known to cause progressive multifocal leukoencephalopathy (PML) in the central nervous system. Hereby, we describe a rare case of PML in a patient without known factors of immunosuppression or use of immunomodulation. A 53-year-old female patient was presented with progressive left-side weakness and tremors in the left hand over a period of two months. The patient was diagnosed with PML based on history, examination, cerebrospinal fluid markers, histopathology, and brain magnetic resonance imaging at presentation. Despite detailed examination, nothing was found in the patient to cause an immunosuppressed state. Therapy was started with mirtazapine with significant neurological improvement.To our knowledge, PML in immunocompetent patient with bening prognosis is a very rare condition. There is also no effective treatment. Our case is a complicated example of this condition.