Asymptomatic diffuse "encephalitic" cerebral toxoplasmosis in a patient with chronic lymphocytic leukemia: case report and review of the literature.

Opportunistic infections account for the majority of central nervous system lesions in adult immunosuppressed patients. In this setting, toxoplasmosis typically manifests as multiple abscesses readily seen on routine neuroimaging studies. Asymptomatic, widely disseminated Toxoplasma cysts without parenchymal reaction are also recognized. In contrast, widespread parasites in the brain parenchyma with an inflammatory "encephalitic" reaction and little or no necrosis have been reported in only four patients with acquired immune deficiency syndrome (AIDS). We describe a 70 year old male with stage IV chronic lymphocytic leukemia complicated by aplastic anemia. Neurological examination and imaging revealed no significant abnormalities. At autopsy, the brain revealed multifocal cysts and free tachyzoites of Toxoplasma gondii with diffuse microglial nodules and no necrosis. To the best of our knowledge, this case represents the first report of the "encephalitic" form of toxoplasmosis in a non-AIDS patient.