Anti-GABA_B receptor encephalitis in a patient with gastric adenocarcinoma

Anti-γ-aminobutyric acid-B (GABA_B) receptor encephalitis is an autoimmune encephalitis associated with antibodies against neuronal cell surface antigens, which are primarily observed with small-cell lung cancer, melanoma, and thymoma. Here, we first report a case on the association between a relatively frequent cancer, gastric adenocarcinoma (GAC), and a rare GABA_B receptor antibody limbic encephalitis. The patient was treated with immunotherapy and combined-drug chemotherapy, which were partially effective in terms of stabilizing the tumor and relieving neurological symptoms. This report indicates that, when patients present with GABA_B receptor antibody limbic encephalitis, regular and broad screening for tumors including gastric adenocarcinoma should also be considered.