Progressive multifocal leukoencephalopathy in a patient with systemic lupus erythematosus.

We describe a patient with longstanding systemic lupus erythematosus (SLE) in remission who presented with recent onset neurological symptoms. Magnetic resonance imaging, followed by a brain biopsy and in situ hybridization, confirmed the diagnosis of progressive multifocal leukoencephalopathy (PML). The clinical findings in this patient emphasize the importance of considering PML in an individual with SLE and neurological abnormalities.