Smoldering myeloma presenting as progressive multifocal leukoencephalopathy: a case report

INTRODUCTION Progressive multifocal leukoencephalopathy is an opportunistic infection occurring in patients with severe cellular immunodeficiency. This case highlights the role of cellular immunodeficiency in the reactivation of John Cunningham virus in a case of an early stage plasmacytoma. CASE PRESENTATION A 76-year-old Caucasian woman presented with progressive left-sided hemiparesis, accompanied by hypoesthesia, hypoalgesia and neuropsychological symptoms. Magnetic resonance imaging demonstrated new hyperattenuating lesions in the right thalamus and left-sided subcortically. A polymerase chain reaction test revealed 4500 copies of John Cunningham virus-deoxyribonucleic acid/ml in cerebrospinal fluid. Human immunodeficiency virus infection was ruled out. A bone marrow biopsy showed an early stage immunoglobulin G-kappa plasmacytoma. Cidofovir (5mg/kg) weekly for three weeks was started. A significant improvement of her neuropsychological symptoms was achieved, but motor system and sensory symptoms did not change. CONCLUSIONS This case shows a rapid course of progressive multifocal leukoencephalopathy with severe residual deficits. In the diagnostic workup of all patients with atypical neurologic symptoms or immunodeficiency, progressive multifocal leukoencephalopathy should be included as a differential diagnosis.