Progressive multifocal leukoencephalopathy in a patient without immunodeficiency

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease caused by the JC virus usually in the context of immunodeficiency. We report a case of PML in a patient without evidence of immunosuppression and highlight several issues relating to diagnosis and management. ### Case report. A 62-year-old right-handed man presented with a 2-year history of progressive left-sided headache, speech difficulties, and hand clumsiness. Three weeks prior to admission he had substantial cognitive decline with concentration and memory difficulties. He reported fatigue and 15-pound weight loss. His background history included hypertension and coronary artery disease. He reported isolated, uncomplicated thoracic shingles 4 years prior. There was no history of alcohol abuse. On examination, he was alert but disoriented to time. He had anomia with expressive aphasia. Comprehension and repetition were intact. He recalled 2 of 3 objects. Motor and sensory examinations were unremarkable. Tendon reflexes were brisk on the right. He walked unassisted but was unsteady on tandem gait. Brain MRI (figure) revealed extensive T2/fluid-attenuated inversion recovery hyperintensities involving the left frontal subcortical white matter, sparing the overlying cortex. There was vasogenic edema with ill-defined patchy contrast enhancement. Figure Brain MRI fluid-attenuated inversion recovery sequence and immunohistopathology of the brain tissue (A) At diagnosis. (B) 2 months post mefloquine. (C) 6 months post mefloquine therapy. (D) The lesion comprises perivascular and interstitial chronic inflammation, atypical astrocytes, …