What's different about teratoma-associated anti-LGI1 encephalitis? A
long-term clinical and neuroimaging case series
Background Anti-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.
Methods Clinical data for 10 people with anti-LGI1 encephalitis and 3
people with anti-N-Methyl-D-aspartate receptor (NMDAR) encephalitis with
teratoma were collected. Microscopic pathological examination and
immunohistochemical (IHC) assay of the LGI1 antibody were performed on
teratoma tissue obtained by laparoscopic oophorocystectomy. Results In
our teratoma associated anti-LGI1 encephalitis case, teratoma pathology
was characterized by mostly thyroid tissue and IHC assay confirmed
partial or focal positive nuclear staining of LGI1 in some tumor cells.
The case was similar to the non-teratoma (NT) group in many ways: age at
onset; percent presenting with rapidly progressive dementia (RPD) and
psychiatric symptoms; hyponatremia; normal cerebrospinal fluid (CSF)
results except for positive LGI1 antibody; bilateral hippocampal
hyperintensity on magnetic resonance imaging (MRI); diffuse slow waves
on electroencephalogram (EEG); good response to immunotherapy and mild
residual cognitive deficit. Her chronic anxiety and status epilepticus
(SE) were the biggest differences compared with NT group. Interestingly,
the case presented many differences compared with anti-NMDAR
encephalitis with teratoma: older onset age, prominent anxiety, SE,
hyponatremia, normal CSF cell count, hippocampal hyperintensity on MRI
and slowly recovered and residual short-term memory impairment.
Conclusion In our series, anti-LGI1 encephalitis included common
clinical features: RPD, faciobrachial dystonic seizures, behavioral
disorders, hyponatremia, T2-MRI hyperintensity of hippocampus and
residual cognitive deficit, but a larger accumulation of cases is needed
to improve our knowledge base.