- An opportunistic infection is a known, although underdiagnosed, complication of systemic lupus erythematosus (SLE). A 48-year-old woman with a recent diagnosis of SLE was admitted to the hospital because of a fever, confused state, and convulsive episode. Her symptoms were interpreted as being compatible with lupus cerebritis. Treatment with methylprednisolone resulted in a temporary improvement in the patient's condition. Nevertheless, during the next few weeks, her physical and mental condition deteriorated, and she died of massive pulmonary emboli. An autopsy revealed no signs of lupus cerebritis; however, disseminated cerebral toxoplasmosis was found. Cerebral toxoplasmosis is a rare complication of SLE that may be misdiagnosed as lupus cerebritis.