An autopsy case of amebic meningoencephalitis. The first Japanese case caused by Balamuthia mandrillaris.

We report here the first case of amebic meningoencephalitis caused by Balamuthia mandrillaris in a 78-year-old Japanese woman with Sjögren's syndrome. Fourteen days before her death, she presented with high fever and lost consciousness and later developed neck stiffness and abducens palsy. Computed tomography scans of the brain demonstrated multiple low-density areas throughout the brain. Neuropathologically, hemorrhagic and necrotic lesions with many amebic trophozoites were scattered in the brain and spinal cord. Granulomatous lesions were only rarely found. The amebas were identified as Balamuthia mandrillaris based on immunofluorescence assay. Clinicopathologically, our case was thought to be an intermediate between primary amebic meningoencephalitis due to Negleria fowleri and granulomatous amebic encephalitis due to Acanthameba species. Essentially, the case was one of an elderly person with suspected immunodeficiency with fulminant necrotic meningoencephalitis and scanty granulomatous lesions of 14 days course.