J Pathol Transl Med.  2019 Sep;53(5):327-331. 10.4132/jptm.2019.05.14.

Amoebic Encephalitis Caused by Balamuthia mandrillaris

• Kum SJ
• Lee HW
• Jung HR
• Choe M
• Kim SP

• KMID: 2459581
• DOI: http://doi.org/10.4132/jptm.2019.05.14

Abstract

We present the case of a 71-year-old man who was diagnosed with amoebic encephalitis caused by Balamuthia mandrillaris. He had rheumatic arthritis for 30 years and had undergone continuous treatment with immunosuppressants. First, he complained of partial spasm from the left thigh to the left upper limb. Magnetic resonance imaging revealed multifocal enhancing nodules in the cortical and subcortical area of both cerebral hemispheres, which were suggestive of brain metastases. However, the patient developed fever with stuporous mentality and an open biopsy was performed immediately. Microscopically, numerous amoebic trophozoites, measuring 20 to 25 µm in size, with nuclei containing one to four nucleoli and some scattered cysts having a double-layered wall were noted in the background of hemorrhagic necrosis. Based on the microscopic findings, amoebic encephalitis caused by Balamuthia mandrillaris was diagnosed. The patient died on the 10th day after being admitted at the hospital. The diagnosis of amoebic encephalitis in the early stage is difficult for clinicians. Moreover, most cases undergo rapid deterioration, resulting in fatal consequences. In this report, we present the first case of B. mandrillaris amoebic encephalitis with fatal progression in a Korean patient.

Keyword

Amoebic encephalitis; Balamuthia mandrillaris; Histopathologic features

MeSH Terms

Aged
Balamuthia mandrillaris*
Biopsy
Brain
Cerebrum
Diagnosis
Encephalitis*
Fever
Humans
Immunosuppressive Agents
Magnetic Resonance Imaging
Necrosis
Neoplasm Metastasis
Rheumatic Fever
Spasm
Stupor
Thigh
Trophozoites
Upper Extremity
Immunosuppressive Agents

Figure

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  Fig. 1. (A) Initial magnetic resonance imaging (MRI) showing multiple ring-enhancing nodules in the cortical and subcortical areas of both cerebral hemispheres. (B) Second MRI showing an increased number and size of the nodules compared to the initial MRI.

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  Fig. 2. Hemorrhagic necrosis (A) is associated with diffuse or perivascular infiltration of amoebic trophozoites (B, C). (C) Elastic stain highlights the trophozoites. Ovoid to round trophozoites, measuring 20 to 25 µm in size, with 1–2 nuclei containing 1–4 nucleoli are noted (D–F).

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  Fig. 3. (A–E) Spherical cysts, measuring 15–20 µm in size, consisting of a rigid double-layered wall are noted. The periodic-acid Schiff (D) and trichrome (E) stains highlight the cysts.

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