An autopsy case of Balamuthia mandrillaris amoebic encephalitis,a rare emerging infectious disease,with a brief review of the cases reported in Japan |
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| Authors: | Kyoko Itoh Kenji Yagita Tomoyoshi Nozaki Harutaka Katano Hideki Hasegawa Koushun Matsuo Youhei Hosokawa So Tando Shinji Fushiki |
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| Affiliation: | 1. Department of Pathology & Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan;2. Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan;3. Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan;4. Division of Neurology, Ohmihachiman Community Medical Center, Ohmihachiman, Japan;5. Division of Pathology, Ohmihachiman Community Medical Center, Ohmihachiman, Japan |
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| 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. |
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| Keywords: | Balamuthia mandrillaris granulomatous amoebic encephalitis MRI necrotizing vasculitis PCR |
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