Autoimmune Hepatitis

 3 types, based on identification of serum autoantibodies

Clinical Issues

• Affects patients of all ages, predominantly women
• Chronic disease by definition but may present clinically as acute or fulminant hepatitis
image Ongoing hepatic injury and scarring with development of cirrhosis and end-stage liver disease
• Many patients have concurrent autoimmune diseases affecting other organs
• Laboratory tests
image Elevated transaminases
image Serum autoantibodies
image Polyclonal hypergammaglobulinemia
• 1st-line therapy is immunosuppression with corticosteroids in combination with azathioprine
image Most patients improve dramatically with treatment
– 65% of patients achieve clinical, biochemical, and histologic remission within 3 years
• Liver transplantation indicated for patients with fulminant hepatitis or decompensated end-stage disease

Microscopic

• Untreated autoimmune hepatitis (AIH) usually presents chronic hepatitis with marked interface activity and lobular injury
• Plasma cells may be prominent but are not constant feature of AIH
• Treated disease may present with normal biopsy or mild chronic hepatitis without specific histologic features
• Severe AIH may mimic acute viral hepatitis
• Extent of inflammation and injury (“grade”) and scarring (“stage”) may be scored
image
Portal InfiltratesTypical portal inflammatory cell infiltrates in autoimmune hepatitis (AIH) contain large numbers of plasma cells. Periportal interface activity image, or “piecemeal necrosis,” is also a characteristic feature.

image
Lobular InjuryDiffuse lobular injury with inflammation image, hepatocyte swelling image, and necrosis is characteristic of AIH.
image
Prominent Plasma CellsProminent lobular inflammatory cell infiltrates with large numbers of plasma cells image and hepatocyte injury are seen in this case of AIH.
image
Bridging NecrosisBoth single-cell necrosis image and areas of confluent or “bridging” necrosis image are seen in this case of AIH. Plasma cells image are prominent.

TERMINOLOGY

Abbreviations

• Autoimmune hepatitis (AIH)

Synonyms

• Lupus/lupoid hepatitis
• Plasma cell hepatitis

Definitions

• Ongoing hepatitis presumed autoimmune in etiology
• 3 types, based on identification of serum autoantibodies
image Type 1
– Most common form
– Antinuclear antibodies (ANA) &/or antismooth muscle antibodies (SMA)
– Bimodal age distribution with peaks from 10-20 and 45-70 years of age
image Type 2
– Antiliver/antikidney microsomal antibodies (anti-LKM-1)
– Most commonly affects children (ages 2-14) but also affects adults
– More severe disease with greater frequency of relapse
image Type 3
– Soluble liver antigen (anti-SLA) or liver pancreas antigen (LP) antibodies
– Usually affects adults aged 30-50
image Subtyping of AIH is of descriptive value only and has no bearing on disease management

ETIOLOGY/PATHOGENESIS

Inciting Event Unknown

• May include infectious agents, drugs, or toxins
• Ongoing immune-mediated liver cell destruction

CLINICAL ISSUES

Epidemiology

• Incidence
image 0.1-1.0 per 100,000 per year in North American and European populations
• Age
image Affects patients of all ages, including children and adolescents
• Sex
image Strong female predominance
– M:F = 1:4
• Ethnicity
image All ethnicities affected

Presentation

• Chronic disease by definition but may present clinically as acute or fulminant hepatitis
image Patients with acute onset of symptoms often found to have clinical, laboratory, &/or histologic signs of chronic liver disease
image Acute presentation may represent flare of previously subclinical disease
image Some patients have no evidence of chronic liver disease, appear clinically similar to acute viral or drug-related hepatitis
• Common signs and symptoms
image Fatigue and lethargy
image Upper abdominal discomfort
image Hepatomegaly
image Jaundice
• Many patients have concurrent autoimmune diseases affecting other organs

Laboratory Tests

• Elevated transaminases, often markedly so
• Hyperbilirubinemia may be seen but is usually mild
• Serum autoantibodies

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Apr 20, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Autoimmune Hepatitis

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