[Neuropathological findings of non-herpetic limbic encephalitis].
In Japan,acute encephalitis similar to herpes simplex encephalitis (HSE) but with no evidence of herpes simplex virus (HSV) infection has been reported. Recently,this type of acute encephalitis has been termed as non-herpetic limbic encephalitis (NHLE) and is indicated to be a possible new subgroup of limbic encephalitis. Only 3 autopsy cases of NHLE have been reported because most patients had a good clinical outcome. However,the 3 autopsy patients who were diagnosed with NHLE on the basis of their typical clinical course died of complications. The neuropathological findings in these 3 cases were similar in that the lesions were exclusively limited to the hippocampus and amygdala. The macroscopic findings in their brains were unremarkable, except for mild swelling. No leptomeningitis, hemorrhagic necrosis, or evidence of any etiologic agent was detected microscopically. The rostral portion of the hippocampus showed small foci characterized by neuronal loss with neuronophagia coexisting with proliferation of microglias, macrophages, hypertrophic astrocytes, and a few lymphocytes. The caudal portion of the hippocampus and amygdala showed neuronal loss with astrocytosis and lymphocytic perivascular cuffing. The abnormal high intensity areas seen on the magnetic resonance imaging scans corresponded well with the regions with astrocytosis. These findings are more similar to those in the case of autoimmune limbic encephalitis than those in the case of HSE. It is likely that these mild neuropathological changes in the case of NHLE are reflective of a good clinical outcome.
Mochizuki
Yoko
Y
Department of Pathology, Tokyo Metropolitan Neurological Hospital, Fuchu-shi, Tokyo, Japan.
Mizutani
Toshio
T
D000328:Adult; D000679:Amygdala / Q000473:pathology*; D001253:Astrocytes / Q000473:pathology; D020803:Encephalitis, Herpes Simplex; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D020363:Limbic Encephalitis / Q000175:diagnosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed