Acanthamoeba castellani encephalitis following partially mismatched related donor peripheral stem cell transplantation.

We describe a case of Acanthamoeba encephalitis in a 45-year-old Caucasian male with acute myelogenous leukemia, who was 140 days status post partially mismatched related donor peripheral blood stem cell transplant. The patient had been transplanted with a highly T-cell-depleted graft, and was not taking any immunosuppressive drugs, and had no history of graft-versus-host disease. He complained of nausea, vomiting, and occasional episodes of confusion; he also had a chronic cough since transplantation. Physical examination was unremarkable except for orthostatic hypotension. Neurologic examination was within normal limits. Laboratory values including electrolytes, white blood cells and platelet counts were normal. Computed tomographic scan of the brain showed a pansinusitis and a hyperdense lesion along the corona radiata suggestive of a fungal abscess. Magnetic resonance imaging showed multifocal areas with mass effect in the posterior fossa and parietal and occipital lobes. The patient had worsening respiratory failure and died three days after admission. At autopsy, specific immunofluorescent staining identified Acanthamoeba castellani in the brain and lungs.