Granulomatous Amoebic Encephalitis Caused by Balamuthia Mandrillaris -Case Report-

Abstract

A 51-year-old immunocompetent Japanese woman presented with a rare case of granulomatous amoebic encephalitis (GAE) caused by Balamuthia mandrillaris. She was brought to our hospital with epilepsy. Magnetic resonance imaging of the brain revealed a homogeneously enhanced solitary mass in the left frontal lobe. Histological diagnosis was made by a biopsy, which suggested lymphomatoid granulomatosis. After that, her neurological condition got worse. New masses were found and had spread across the whole brain. She died 2 months later of cerebral hernia. Autopsy revealed that the patient had GAE caused by Balamuthia mandrillaris. GAE is usually fatal, and is difficult to diagnose except at autopsy. Therefore, awareness of this disease is important, and earlier diagnosis and the development of a better therapeutic strategy will improve clinical outcome.

An autopsy case of Balamuthia mandrillaris amoebic encephalitis, a rare emerging infectious disease, with a brief review of the cases reported in Japan

“…The first case was reported by Shirabe et al ., in which a 78‐year‐old woman with suspected immunodeficiency demonstrated fulminant hemorrhagic and necrotic meningoencephalitis, as well as scanty granulomatous lesions with many amoebic trophozoites. In another two cases, BAE showed extensive fibrinoid necrosis of the medium and small arteries, with perivascular infiltration by trophozoites and amoebic cysts . In the present case, there was less granulomatous inflammation, but more extensive hemorrhagic and necrotic lesions were observed associated with necrotic vasculitis showing destruction of the medial wall of arteries and hemorrhagic necrosis in the surrounding areas.…”

“…In the present case, there was less granulomatous inflammation, but more extensive hemorrhagic and necrotic lesions were observed associated with necrotic vasculitis showing destruction of the medial wall of arteries and hemorrhagic necrosis in the surrounding areas. In Japanese cases, it could be argued that the more likely frequent neuropathological changes in BAE would be fulminant meningoencephalitis with necrotizing vasculitis, compared with cases reported outside Japan. The reason for this assumption might be that all of the Japanese cases were subjects older than 50 years, and 4/7 were immunocompromised individuals due to diabetes mellitus, prolonged steroid treatment, a postoperative state, or being an HTLV‐1 carrier.…”

“…[2][3][4] Since its identification in 1986 5 and the first human cases in 1991, 6,7 Balamuthia mandrillaris has been increasingly recognized as an etiologic agent of amoebic encephalitis in human hosts, and so far, more than 200 cases have been reported worldwide. [8][9][10][11][12][13][14][15][16][17] The neuropathology in these cases is characterized by brain edema and subacute necrotizing hemorrhagic encephalitis. The granulomatous inflammation, composed of foamy macrophages and multinucleated giant cells accompanied by lymphocytes, is occasionally seen with amoebic-induced thrombotic angiitis, producing large areas of hemorrhage, infarction and necrosis.We herewith report an autopsy case of B. mandrillaris amoebic encephalitis (BAE) in an elderly man, who showed multiple hemorrhagic and necrotic lesions associated with marked necrotizing vasculitis and less granulomatous inflammation.…”

Successful Treatment of Granulomatous Amoebic Encephalitis with Combination Antimicrobial Therapy

“…However, occlusion of the blood vessels and bleeding have been reported in the brain tissue of patients with GAE, with vasculitis assumed to be the cause. Although there is usually invasion of small vessels, and necrosis is often observed over a small region, cases resulting in large vessel arterial infarction, as observed in this case, have also been reported (10,13). The same mechanism has been reported to occur in cases of fungal meningitis, such as that involving aspergillosis, toxoplasma encephalitis, tuberculous meningitis and bacterial meningitis.…”

“…Although brain biopsies were performed antemortem in these cases, the biopsy findings did not lead to a diagnosis (8)(9)(10). Unlike N. fowleri (11), Acanthamoeba species and B. mandrillaris are usually not visible in the CSF on microscopic examinations antemortem.…”