Viral, autoimmune and metabolic hepatitis — structured clinical encounter

Station brief (candidate)

You are the paediatric registrar in a general paediatric clinic. A thirteen-year-old girl is referred with three months of worsening fatigue, yellowing of the eyes, acne, loss of her periods and aching joints. Her immunoglobulin G is twenty-five grams per litre and her antinuclear antibody is positive at one in six hundred forty. The viral hepatitis serology, including hepatitis B and C, is negative. The liver biopsy shows interface hepatitis with a dense plasma-cell infiltrate. The team asks you to establish the diagnosis and its type, to apply the diagnostic score, to outline the induction treatment with the safety checks, to exclude the overlap condition, and then to counsel the family on the outlook and the monitoring. You have twelve minutes with the team and five minutes for examiner discussion. [8]

Information available on request

• Immunoglobulin G twenty-five grams per litre; antinuclear antibody positive at one in six hundred forty; anti-smooth-muscle antibody negative; anti-liver-kidney-microsomal antibody negative. [9]
• Viral hepatitis serology negative: HBsAg negative, anti-HCV negative, IgM anti-HAV negative. [8]
• Liver biopsy: interface hepatitis with a plasma-cell infiltrate, consistent with autoimmune hepatitis, with mild periportal fibrosis. [8]
• Thyroid function normal; no diarrhoea or bloody stools; inflammatory bowel disease screen not yet done. [8]

Candidate tasks

1. Give the diagnosis and the type, and explain the reasoning. [9]
2. Apply the simplified International Autoimmune Hepatitis Group score and state whether it is definite or probable. [9]
3. Outline the induction treatment with the doses and the safety check before the steroid-sparing agent. [8]
4. Name the overlap condition to exclude, how to exclude it, and the association that makes it likely. [8]
5. Counsel the family on the relapsing course, the duration of treatment and the monitoring. [8]

Examiner discussion points

• Why is the thiopurine methyltransferase activity checked before the full azathioprine dose? (To avoid fatal myelosuppression in the deficient child.) [8]
• What is the role of budesonide, and in which child is it avoided? (A less systemically absorbed steroid for the non-cirrhotic; avoided in cirrhosis because of portal-systemic shunting.) [8]
• What distinguishes autoimmune hepatitis from autoimmune sclerosing cholangitis? (Bile-duct injury on cholangiography and the inflammatory bowel disease association.) [8]
• When is liver transplantation considered? (Fulminant presentation or progression to cirrhosis despite treatment.) [8]
• What else must be excluded before accepting the autoimmune diagnosis? (Wilson disease, because the chronic hepatitis and the young age overlap; a ceruloplasmin and urinary copper close the gap.) [11]

Marking domains

• Clinical reasoning: recognises the insidious autoimmune hepatitis presentation and distinguishes type 1 from type 2 on the antibody profile. [8]
• Investigation: applies the simplified score correctly and scores eight out of eight for definite disease. [9]
• Management: gives the prednisolone-and-azathioprine induction with correct doses and the thiopurine methyltransferase check, and plans the taper and maintenance. [8]
• Safety and breadth: excludes overlap with autoimmune sclerosing cholangitis and inflammatory bowel disease, and excludes Wilson disease. [8] [11]
• Communication: counsels on the relapsing course, the years of treatment, the steroid toxicity monitoring and the planned transition. [8]