A liver biopsy from a 45-year-old woman with autoimmune hepatitis shows plasma cell-rich periportal inflammation, rosette formation of hepatocytes, and emperipolesis (penetration of lymphocytes into hepatocyte cytoplasm). The characteristic autoantibody in Type 2 AIH is:

• A Anti-smooth muscle antibody (ASMA) against F-actin
• B Antimitochondrial antibody (AMA-M2) against PDC-E2
• C Anti-dsDNA antibody
• D Anti-LKM1 (anti-liver-kidney microsomal type 1) antibody against CYP2D6 ✓

Explanation

Type 2 AIH (more common in children and young women) is characterized by anti-LKM1 (anti-liver-kidney microsome type 1) antibodies directed against cytochrome P450 2D6 (CYP2D6), with some patients also having anti-LC1 (liver cytosol type 1) antibodies. Type 1 AIH features ANA and/or anti-smooth muscle antibody (ASMA against F-actin) — this is the more common adult form. Antimitochondrial antibody (AMA-M2 against PDC-E2) is the hallmark of primary biliary cholangitis (PBC), not AIH.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.