Autoimmune hepatitis (AIH) is a progressive idiopathic liver disease characterised by liver inflammation.
Pathophysiology
In AIH, it is thought that genetically susceptible individuals develop T-cell mediated autoimmune attacks on the liver in response to an unknown trigger, leading to inflammation, necrosis, fibrosis and cirrhosis of liver tissue.
Clinical Features
- Patients may be asymptomatic, or they may show signs of hepatitis such as fatigue, anorexia, jaundice or right upper quadrant pain.
- History of other autoimmune disease
- Tends to affect women
- Amenorrhoea is a common finding
- Arthralgia may be present
- Alternatively, if patients have developed cirrhosis that may present with stigmata of chronic liver disease i.e. spider naevi, ascites etc.
Investigations
Bloods
- Liver function tests: ALT and AST usually high. ALP and gamma-GT may be raised, but they can be normal as well.
- Bilirubin: Elevated
- FBC, U&E, Clotting: Baseline
- Autoantibodies
- Antinuclear antibodies (ANA)
- Anti-smooth muscle antibodies (ASMA)
- Antibodies to liver-kidney microsome type 1 (anti-LKM1)
- Anti-liver cytosolic-1 (LC-1)
- Serum immunoglobulins: Raised in AIH, particularly IgG
- Hepatitis screen: Rule out this as an underlying cause of presentation
Imaging
- Abdominal US: Rule outbiliary obstruction
- CT/MRI
Special Tests
- Liver biopsy: The British Society of Gastroenterology guidelines state that liver biopsy should be performed for diagnosing AIH unless there are contraindications.
- Interface hepatitis is a typical feature, which shows inflammation at the junction between the portal tract and hepatocytes.
- Lymphocytic/lymphoplasmocytic infiltration in portal tracts
- Hepatocellular rosettes: These are small rings of hepatocytes which surround a small (not always visible) lumen. They indicate regeneration of hepatocytes after lobular injury.
- Hepatocyte necrosis
Classification
There are two main types of AIH – type I and type II.
- In type I, ANA or ASMA are positive in serum.
- Type II is associated with positive anti-LKM1 or LC-1, and also tends to present in childhood or adolescence.
Management
The mainstay of treatment in AIH is immunosuppressive therapy with prednisolone and azathioprine (usually given in combination). Patients with severe decompensated cirrhosis or poor response to medical therapy may require liver transplantation.
References
https://www.bsg.org.uk/wp-content/uploads/2019/12/BSG-guidelines-for-the-management-of-autoimmune-hepatitis.pdf?x56907
https://www.ncbi.nlm.nih.gov/books/NBK459186/
https://www.karger.com/Article/Fulltext/440747
