Abstract
Anti-γ-aminobutyric acid B receptor (anti-GABA(B)R) encephalitis is a rare type of autoimmune encephalitis (AE). Although it responds well to immunomodulating therapy and has favorable prognosis, anti-GABA(B)R AE has often been misdiagnosed as infectious encephalitis. Herein, we present a case of a 59-year-old female with anti-GABA(B)R AE associated with small cell lung cancer (SCLC) that was once misdiagnosed as infectious encephalitis. Our findings increase the awareness that patients presenting with a clinical trial of cognitive impairment, seizures and SCLC may harbor AE. Our case also highlights the importance of anti-SOX1 antibody in the detection of SCLC.