Abstract
Autoimmune liver diseases, such as autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC), present significant diagnostic and therapeutic challenges due to overlapping features and potential for severe complications. AIH-PBC overlap syndrome, a rare condition, combines characteristics of both diseases but lacks standardized treatment protocols. We present the case of a 42-year-old male with elevated liver function tests, pruritus, flatulence, and epigastric pain. Laboratory findings revealed a cholestatic liver function pattern, a highly positive antinuclear antibody titer, weakly positive anti-smooth muscle antibody, elevated immunoglobulin G, and negative viral and anti-mitochondrial antibody markers. Diagnostic imaging, including abdominal ultrasound and magnetic resonance cholangiopancreatography, demonstrated mild fatty liver, slight irregularity in the left biliary duct wall, and a normal common bile duct without significant abnormalities. Liver biopsy confirmed chronic hepatitis with dense portal lymphoplasmacytic infiltrate, scattered eosinophils, moderate interface hepatitis, and mild lobular necroinflammation, consistent with AIH-PBC overlap syndrome. The Paris criteria were used to establish the diagnosis. Treatment with ursodeoxycholic acid, prednisolone, and azathioprine resulted in significant clinical and biochemical improvement.