A 50-year-old woman presents with pruritus and fatigue. Labs show elevated alkaline phosphatase and gamma-glutamyl transferase. Total bilirubin is normal. Liver biopsy reveals florid duct lesions with lymphocytic destruction of interlobular bile ducts. Which autoantibody is most specifically associated with this condition?
- A Anti-smooth muscle antibody
- B Anti-mitochondrial antibody ✓
- C Anti-nuclear antibody
- D Anti-LKM-1 antibody
Correct answer: B. Anti-mitochondrial antibody
Explanation
The clinical picture and florid duct lesions indicate primary biliary cholangitis. Anti-mitochondrial antibody, specifically the M2 subtype targeting the pyruvate dehydrogenase complex, is present in 90 to 95 percent of patients and is the serologic hallmark. Anti-smooth muscle and anti-nuclear antibodies are associated with autoimmune hepatitis. Anti-LKM-1 is associated with type 2 autoimmune hepatitis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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