Anti-GABAB receptor encephalitis in a patient with gastric adenocarcinoma

Anti-γ-aminobutyric acid-B (GABAB) 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 GABAB 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 GABAB receptor antibody limbic encephalitis, regular and broad screening for tumors including gastric adenocarcinoma should also be considered.