Autoimmune hepatitis (AIH) - concise clinical guide
Overview
Autoimmune hepatitis (AIH) is a chronic immune‑mediated liver disease caused by loss of tolerance to hepatocyte antigens. It produces a predominantly hepatocellular pattern of injury, can progress to fibrosis and cirrhosis, and occasionally presents as severe acute hepatitis or acute liver failure. AIH is an established autoimmune cause of chronic liver disease in UK guidance (NICE NG50).
Epidemiology
- Most commonly affects women (≈70%).
- Typical age at presentation: young to middle‑aged adults (≈15-40 years), but can occur at any age.
Pathophysiology and histology
- Aberrant adaptive immune responses with reduced regulatory T‑cell control lead to activation of autoreactive T and B cells and production of autoantibodies.
- Histological hallmark: interface (piecemeal) hepatitis with portal/periportal lymphoplasmacytic infiltrates (often with plasma cells) and hepatocyte necrosis.
- Chronic inflammation causes fibrosis and can progress to cirrhosis.
Clinical features Presentation is variable:
- Insidious: fatigue, malaise, arthralgia, vague abdominal discomfort.
- Typical hepatitic features: jaundice, anorexia, nausea, right upper‑quadrant pain.
- Advanced disease: signs of portal hypertension or decompensation (ascites, encephalopathy).
- Acute presentations: severe hepatitis or acute liver failure in a minority.