18F\DOPA PET showed increased uptake of the medial aspects of the lesion (not shown) while EEG showed remaining frontotemporal slowing. the lesion was suggested and performed three months after the first symptoms. Post surgery, the patient did not develop fresh neurological deficits and was sent to rehabilitation. Here, the patient developed frequent complex\partial seizures followed by right\sided hemiparesis, disorientation, long\enduring somnolence and severe memory disturbances. Six months after the initial symptoms, the patient was admitted to our Division of Neurology. Repeated cerebral MRI showed status after resection of the remaining hippocampus. EEG showed severe generalized slowing, while CSF again was normal. Open in a separate window Number 1 ? Microscopic Pathology By H&E, the cellularity adjacent to the hippocampal AMI5 formation was improved by astrocytes with large cytoplasm and AMI5 accompanying macrophages and lymphocytes (Number ?(Number1C).1C). Immunostaining exposed several GFAP\positive cells with isomorphic, reactive rather than pleomorphic fibrillary morphology (Number ?(Figure1D).1D). Further, these cells did not stain positive for MAP2, in favor of a reactive rather than neoplastic process (not demonstrated). No improved mitotic activity, vascular proliferates or necrosis were present. In addition, molecular pathology did not reveal IDH mutations. Some spread CD8+ T lymphocytes were detected (Number ?(Figure1E).1E). Occasional CD138+ plasma cells were mostly localized perivascular as well as sparsely distributed in the parenchyma. Abundant CD68+ triggered microglia cells were found in the limbic constructions. H&E staining showed reduced neuronal denseness, especially in CA4 (asterisk), whereas granule cells (arrow) of the dentate gyrus were spared (Number ?(Number1C).1C). There were also several considerably damaged neurons with hypereosinophilic cytoplasm and pyknotic nuclei (arrow head/place). Some neurons showed considerable deposition of match C9neo (end complex; arrows) (Number ?(Figure1F).1F). What is your analysis? Diagnosis Anti\leucine rich glioma inactivated 1 (LGI1)autoimmune\mediated limbic encephalitis. Conversation Lesions of the hippocampus are frequently associated with symptomatic epileptic seizures. However, a diffuse swelling hippocampus with contrast enhancement upon MRI may indicate a higher Rabbit Polyclonal to USP6NL grade glioma or inflammatory changes in the context of a limbic encephalitis. Histopathological examination of the resected hippocampus in our case showed increased cellularity, in part due to prominent astroglial proliferation. However, molecular pathology and marker manifestation patterns made the AMI5 analysis AMI5 of a glioma, highly suggested from the imaging findings, unlikely. In contrast, neuronal loss in association with neuron\specific AMI5 complement end\complex deposition, microglia activation and infiltration with CD8+ T lymphocytes was found. The lack of lymphoblasts and presence of different populations of immunocompetent cells ruled out main CNS lymphoma. Testing for antineuronal antibodies exposed anti\LGI1 antibodies in serum (1:100) and CSF (1:10). Anti\LGI1 encephalitis (LGI1\E) is definitely a disease mainly affecting elderly males 1. Epileptic seizures, cognitive decrease, T2 mesiotemporal lobe hyperintensities and hyponatremia are common findings. CSF findings are mostly normal. Multiple mechanisms may play a role in the pathogenesis of LGI1\E. Firstly, the autoantibodies seem to disrupt the LGI1\ADAM connection followed by AMPA receptor downregulation 3. In addition, neuron\specific complement end\complex deposition, as found in our case and reported previously 2, probably contributes to neuronal death in LGI1\E. This mechanism seems to be absent in anti\NMDA receptor encephalitis, the most common form of autoimmune encephalitis 2. Our case demonstrates that LGI1\E can mimic high\grade glioma in imaging studies. Therefore, the awareness of this differential analysis and overall performance of neuronal autoantibody screening are crucial to initiate specific treatment. Due to good response to immunotherapy reported for LGI\E, chronic phases with hippocampal atrophy and prolonged cognitive dysfunction are avertable. Acknowledgment We say thanks to the patient and his family for his or her permission to statement the case history. J.L. thanks Martina Leis for the excellent technical assistance. J.C.K. is definitely supported from the Else Kr?ner\Fresenius Stiftung having a give in aid (EKFS\Promotionskolleg Neuroimmunology)..