What’s Different about Teratoma-Associated LGI1 Encephalitis? A Long-Term Clinical and Neuroimaging Case Series

Abstract

Background Leucine-rich glioma-inactivated 1 (LGI1) encephalitis is clinically heterogeneous, especially at presentation, and though it is sometimes found in association with tumor, this is by no means the rule. The aim of this study is to report a case of teratoma-associated LGI1 encephalitis, to summarize a retrospective series of LGI1 encephalitis and compare them. Methods Clinical data for 10 people with LGI1 encephalitis were collected. Patients were divided into those with and without associated teratoma, and compared for clinical characteristics. Microscopic pathological examination and immunohistochemical (IHC) assay of the LGI1 antibody were performed on teratoma tissue obtained by laparoscopic oophorocystectomy. Results The LGl1 patient with teratoma was similar to the non-teratoma (NT) group in many ways: age at onset (average 47.3 in NT group); percent presenting with rapidly progressive dementia (RPD) (67% of NT group) and psychiatric symptoms (33%); hyponatremia (78%); normal cerebrospinal fluid results except for positive LGI1 antibody (78%); bilateral hippocampal hyperintensity on magnetic resonance imaging (MRI) (44%); diffuse slow waves on electroencephalography (EEG) (33%); good response to immunotherapy (67%); and mild residual cognitive deficit (22%). Her chronic anxiety and presentation with status epilepticus were the biggest differences compared with the NT group. Teratoma pathology was characterized by mostly thyroid tissue and IHC assay confirmed positive LGI1 expression. Conclusion In our series, LGI1 encephalitis included common clinical features: RPD, faciobrachial dystonic seizures, behavioral disorders, hyponatremia, T2-MRI hyperintensity of hippocampus and residual cognitive deficit. We observed some differences in our case with teratoma, but a larger accumulation of cases is needed to improve our knowledge base.