A 35-year-old woman is evaluated for persistently elevated ALT (95 to 140 U/L over 6 months), hypergammaglobulinemia (IgG 2400 mg/dL), positive ANA (1:640) and anti-smooth muscle antibody, negative viral hepatitis markers, and no alcohol or drug use. Liver biopsy shows interface hepatitis with rosette formation and plasma cell infiltration. Using the simplified AIH score, which combination of findings gives the highest diagnostic weight?

• A Positive autoantibodies (ANA/SMA ≥1:80) + typical histology
• B Elevated IgG >1.1× ULN + exclusion of viral hepatitis + typical histology
• C ANA ≥1:40 + IgG >ULN + absence of viral hepatitis
• D Positive autoantibodies + elevated IgG + typical histology + exclusion of viral hepatitis ✓

Explanation

The simplified AIH diagnostic score assigns points across four domains: autoantibody titers (ANA/SMA or anti-LKM1), IgG level, histology (interface hepatitis is typical), and exclusion of viral hepatitis. A score ≥6 indicates probable AIH and ≥7 definite AIH. Having all four domains present (autoantibodies + elevated IgG + typical histology + no viral hepatitis) yields the highest score and a definite diagnosis.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.