Central nervous system systemic lupus erythematosus mimicking progressive multifocal leucoencephalopathy

The case is reported of a patient with central nervous system systemic lupus erythematosus (SLE) with features of progressive multifocal leucoencephalopathy (PML) seen clinically and by magnetic resonance imaging. A brain biopsy sample showed microinfarcts. The use of magnetic resonance imaging and IgG synthesis rates in evaluating central nervous system lupus, the co-occurrence of SLE and PML, and the differentiation of these entities by magnetic resonance imaging and by histology are considered.