infectious diseases
Granulomatous Amebic Encephalitis
Diagnosis of Granulomatous Amebic Encephalitis
Head CT and/or MRI with contrast Cerebrospinal fluid analysis Biopsy of skin lesions Diagnosis of granulomatous amebic encephalitis is often postmortem. In patients withAcanthamoebainfections of the brain, CT with contrast and MRI may show single or multiple space-occupying lesions with ring enhancement, most commonly in the temporal and parietal lobes. In cerebrospinal fluid (CSF), white blood cell (WBC) count (predominantly lymphocytes) is elevated, but trophozoites are rarely seen. These tests help exclude other possible causes but usually cannot confirm the diagnosis. Visible skin lesions often contain amebas and should be biopsied; if detected, amebas may be cultured and tested for drug sensitivity. Brain biopsy is often positive and should be considered if granulomatous amebic encephalitis is suspected. Polymerase chain reaction (PCR)–based assays are available in specialized reference laboratories. In patients withB. mandrillarisinfection of the brain, CT and MRI, both with contrast, typically show multiple nodular, ring-enhancing lesions. Intralesional hemorrhage is an important radiologic clue. In CSF the WBC count is elevated (predominantly lymphocytes), the glucose is normal or low, and the protein is often markedly elevated.B. mandrillarisis rarely identified in CSF. Microscopic examination plus PCR-based and immunohistochemical techniques can identifyB. mandrillarisin biopsies of brain or skin lesions. 