A Case of Autoimmune Hepatitis Initially Manifesting as Hepatic Encephalopathy.

Autoimmune hepatitis (AIH) is a T-cell-mediated liver disease characterized by elevated transaminases, circulating autoantibodies, hypergammaglobulinemia, and interface hepatitis. A 66-year-old female patient visited our department due to recurrent episodes of altered consciousness, sleep-wake inversion, and asterixis, indicating hepatic encephalopathy (HE). Her liver biopsy results clearly demonstrated interface hepatitis. The patient's severe HE does not parallel her relatively stable liver function and was attributed to a wide retroperitoneal collateral vein shunting blood directly into the inferior vena cava, bypassing the liver, and allowing excess neurotoxins to enter the central nervous system. Due to the unfavorable benefit-risk ratio of embolization and the patient's stable liver function, non-invasive treatments were adopted, and prednisolone was discontinued. The patient experienced no further episodes of HE thereafter. To the best of our knowledge, this is the first AIH case with a spontaneous portosystemic shunt directly shunting blood into the inferior vena cava. A crucial lesson from this case is that when HE cannot be fully explained by liver dysfunction, abdominal CT scans should be carefully inspected for possible anatomical variations. This case also underscores the importance of a multidisciplinary approach in managing AIH in elderly patients, who may benefit more from a tailored treatment regimen rather than strictly following standard treatment guidelines.