Fatal granulomatous amoebic meningoencephalitis due to Balamuthia mandrillaris

Abstract

Amoebic infections of the central nervous system (CNS) are very rare and usually fatal. A 33-year-old Bolivian male injured his elbow 18 months ago in an accident and, months later, developed multiple skin lesions. He was admitted with confusion, and brain images showed large multifocal lesions with mass effect. Review of the skin biopsy revealed the presence of amoebic trophozoites within a granulomatous inflammation. Despite treatment, he continued to deteriorate and died 17 days after admission. The brain was swollen with prominent uncal herniation, and the leptomeninges showed patchy exudate. Coronal sections revealed widespread hemorrhagic and necrotic lesions. Histology confirmed granulomatous amoebic meningoencephalitis (GAM) with the presence of amoebic trophozoites and occasional cysts. Post-mortem culture confirmed Balamuthia mandrillaris. GAM due to B. mandrillaris may occur in any age group, may or may not be associated with immunosuppression, and is present worldwide. It usually has a subacute and fatal course from hematogenous dissemination of chronic skin or lung lesions.