A 14-year-old girl presents with jaundice and markedly raised transaminases. ANA and anti-smooth muscle antibody are negative. Liver biopsy shows interface hepatitis with plasma cell infiltrate. Which additional autoantibody finding would establish type 2 autoimmune hepatitis?
- A Anti-mitochondrial antibody
- B Perinuclear anti-neutrophil cytoplasmic antibody
- C Anti-liver kidney microsomal type 1 antibody ✓
- D Anti-soluble liver antigen antibody
Correct answer: C. Anti-liver kidney microsomal type 1 antibody
Explanation
Type 2 autoimmune hepatitis is defined by anti-LKM1 antibodies, directed against CYP2D6, and occurs predominantly in children and adolescents, often girls, who are characteristically negative for ANA and anti-smooth muscle antibody. Perinuclear ANCA marks type 1 disease, anti-mitochondrial antibody indicates PBC, and anti-soluble liver antigen can occur in either type but is not the defining marker of type 2. Recognizing the pediatric ANA-negative presentation is key.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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