A Rare Case of Autoimmune Hepatitis-Primary Biliary Cholangitis Overlap Syndrome in a Male Patient.

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.