A 58-year-old woman with known primary biliary cholangitis presents with worsening fatigue and a new pruritus unresponsive to cholestyramine. Labs show ALP 420 U/L, total bilirubin 3.1 mg/dL, and IgM 890 mg/dL. She has been on ursodeoxycholic acid for 3 years. Which finding would MOST strongly suggest overlap syndrome with autoimmune hepatitis rather than pure PBC progression?

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