History and admission findings: A 62-year-old woman developed paresis in her right arm within several weeks. She was being treated with methylprednisolone (4 mg daily) and chlorambucil (2 mg every other day) for systemic lupus erythematodes (SLE), which was now in remission. Neurological examination on admission revealed a right flaccid hemiparesis, predominantly of the right arm. The physical examination was otherwise unremarkable.
Investigations: Magnetic resonance imaging (MRI) (T2 weighted) showed hyperintense changes in the subcortical medullary layer of the left precentral gyrus without perifocal oedema or abnormal contrast medium uptake, which argued against progressive cerebral ischaemia or tumour. Blood and cerebrospinal fluid (CSF) showed no abnormalities except leukopenia and a raised antinuclear antibody titre. Progressive paralysis of the right side of the body after 2 years of immunosuppressive treatment, the MRI findings and an essentially normal CSE suggested progressive multifocal leucoencephalopathy (PML), confirmed by polymerase chain reaction (PCR) demonstrating JC-virus DNA in serum and CSF.
Treatment and course: As a result of the CNS infection with papovavirus JC, an opportunistic infection of the central nervous system, which is usually fatal, occurred. The cerebral changes spread within a few weeks, despite of the immunosuppressive drugs having been discontinued. The pareses progressed further and a marked personality disorder of organic origin ensued.
Conclusion: While efficacious immunosuppressive drugs against autoimmune disease are available, their use risks the occurrence of life-threatening opportunistic infections.