Autoimmune hepatitis type 1 in a middle-aged female with ulcerative colitis: Navigating the diagnostic overlap and achieving sustained remission

Autoimmune hepatitis (AIH) is a chronic, immune-mediated inflammatory liver disease that, without timely recognition and treatment, progresses to cirrhosis and liver failure. Type 1 AIH, the predominant subtype, is characterized by the presence of antinuclear antibody (ANA) and/or anti-smooth muscle antibody (ASMA), accounting for approximately 80% of AIH cases worldwide. 
We report a 55-year-old Caucasian woman with a background of quiescent ulcerative colitis who presented with a six-week history of progressive fatigue, anorexia, right upper quadrant discomfort, and new-onset jaundice. Laboratory investigations revealed markedly elevated serum aminotransferases (ALT 520 U/L, AST 480 U/L), total bilirubin of 4.2 mg/dL, and significantly elevated serum immunoglobulin G (IgG) at 3,200 mg/dL. Autoimmune serology demonstrated strongly positive ANA (1:320, homogeneous pattern) and ASMA (1:160). 
Magnetic resonance cholangiopancreatography (MRCP) excluded primary sclerosing cholangitis. Liver biopsy confirmed moderate-to-severe histological activity with florid lymphoplasmacytic infiltrate, interface hepatitis, emperipolesis, hepatocyte rosette formation, and early bridging fibrosis (Metavir F2). The International Autoimmune Hepatitis Group (IAIHG) simplified score was calculated at 7, confirming definite AIH Type 1. Dual immunosuppressive therapy with prednisone and azathioprine achieved complete biochemical remission by month four.
This case illustrates the diagnostic complexity of AIH Type 1 in a middle-aged woman with concurrent inflammatory bowel disease, underscoring the critical role of multidisciplinary evaluation, systematic overlap exclusion, and structured long-term surveillance.