[Fatal neurological side effect of anti-CD20 antibody treatment]

Progressive multifocal leukoencephalopathy (PML) is a rare, often fatal infection of the central nervous system caused by reactivation of John Cunningham virus (JCV). The case of a 59-year-old woman presenting with neurological disorders after treatment of her relapsed lymphoma with rituximab, among others, is reported. Magnetic resonance imaging showed fast-growing white matter lesions of both hemisphere and cerebellar that were neither space-consuming nor enhancing contrast media. Clinical and radiological suspicion of PML was confirmed by detection of JCV-DNA in cerebrospinal fluid. The patient died from devastating neurological decline only 11 days after the diagnosis was made. Due to the wider indication of monoclonal antibodies in almost every medical specialty we must always consider iatrogenic PML in addition to classic PML associated with acquired immunodeficiency syndrome (AIDS).