title: An autopsy case of Balamuthia mandrillaris amoebic encephalitis, a rare emerging infectious disease, with a brief review of the cases reported in Japan.
abstract: Balamuthia mandrillaris is an amoeba found in fresh water and soil that causes granulomatous amoebic encephalitis. We report herein an autopsy case of B. mandrillaris amoebic encephalitis, which was definitely diagnosed by PCR. An 81-year-old man, who had Sjögren's syndrome, manifested drowsiness 2 months before his death with progressive deterioration. Neuroimaging demonstrated foci of T2- and fluid-attenuated inversion recovery high and T1 low-intensity with irregular post-contrast ring enhancement in the cerebral hemisphere, thalamus and midbrain. Pathologically, multiple hemorrhagic and necrotic lesions were found in the cerebrum, thalamus, midbrain, pons, medulla and cerebellum, which were characterized by liquefactive necrosis, marked edema, hemorrhage and necrotizing vasculitis associated with the perivascular accumulation of amoebic trophozoites, a few cysts, and the infiltration of numerous neutrophils and microglia/macrophages. The trophozoites were ovoid or round, 10-60 μm in diameter, and they showed foamy cytoplasm and a round nucleus with small karyosome in the center. The PCR and immunohistochemistry from paraffin-embedded brain specimens revealed angioinvasive encephalitis due to B. mandrillaris. Human cases of B. mandrillaris brain infection are rare in Japan, with only a few brief reports in the literature.
authors.affiliation: Department of Pathology & Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Itoh
authors.forename: Kenji
authors.initials: K
authors.lastname: Yagita
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Nozaki
authors.forename: Harutaka
authors.initials: H
authors.lastname: Katano
authors.forename: Hideki
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Koushun
authors.initials: K
authors.lastname: Matsuo
authors.forename: Youhei
authors.initials: Y
authors.lastname: Hosokawa
authors.forename: So
authors.initials: S
authors.lastname: Tando
authors.forename: Shinji
authors.initials: S
authors.lastname: Fushiki
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000562:Amebiasis / Q000150:complications / Q000473:pathology*; D059611:Balamuthia mandrillaris / Q000302:isolation & purification*; D001921:Brain / Q000469:parasitology / Q000473:pathology*; D020808:Central Nervous System Protozoal Infections / Q000150:complications / Q000473:pathology*; D021821:Communicable Diseases, Emerging / Q000150:complications / Q000473:pathology; D004660:Encephalitis / Q000150:complications / Q000473:pathology*; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D012859:Sjogren's Syndrome / Q000150:complications
keywords: Balamuthia mandrillaris; MRI; PCR; granulomatous amoebic encephalitis; necrotizing vasculitis