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Autoimmune Hepatitis (AIH) is an unresolving inflammation of liver, unknown cause:
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Characterized by interface hepatitis (histology), autoantibodies & hypergammaglobulinemia (serum)
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Types of AIH:
Features
Type 1 (Classic)
Type 2
Type 3 (Least Established Form)
Predominant age
Adult (some children)
Child (girls > boys)
All ages ? if really a variant of Type 1 AIH
Auto Antibodies
LKM1ˆ
anti-SLA*ˆ
ANA, p-ANCA
Liver cytosol 1
Anti-Actin
Organ-specific Ab
± (thyroid)
± (thyroid, parietal cells)
?
Autoantigen
Unknown
P450 2D6 (CYP2D6)
tRNP
HLA phenotype
B8, DR3, DR4
DR3, DR7
DR3
Fulminant onset
Possible (but rare)
Possible
Unknown
Concurrent disease
40% (see below)
32% (see below)
60% (see below)
Gamma globulin ↑
Yes
Slight
Moderate
Progress Cirrhosis
35%
80%
Probably
Steroid responsive
Yes
Yes
Yes
* anti-smooth muscle antibody,ˆ anti-liver/kidney microsome type 1,*ˆ anti-soluble liver antigen
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Overlap or Variant Syndrome:
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Autoimmune Hepatitis & PBC or PSC; Has high titers of AMA and cholestasis; See also Liver- PBC (Chapter 4.23)
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F:M = 5:1, can occur at any age but typically before 4th decade; Represents <10% of all chronic hepatitis in the U.S. but 6% of transplants
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Concurrent immunologic diseases can be present in patients, most common: autoimmune thyroiditis, ulcerative colitis, Graves, synovitis, RA
Others: |
Celiac sprueCoomb’s + hemolytic anemiaCyroglobulinemiaDermatitis herpetiformis |
Erythema nodosumFocal myositisGingivitisGlomerulonephritis |
ITPInsulin DMIritisLichen planus |
Myasthenia gravisNeutropeniaPericarditisPeripheral neuropathy |
Pernicious anemiaPleuritisPyoderma gangrenosum |
Sjogren’sSLEUrticariaVitiligo |
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Differential diagnosis |
Diagnostic tests (See each corresponding diagnosis/chapter for details) |
Wilson’s |
Copper studies: ↓ ceruloplasmin, ↓ serum copper, ↑ urinary copper | |
Cholangiography: Focal biliary strictures; Liver biopsy: fibrous obliterate changes | ||
Auto Antibodies: AMA >1:40; Liver biopsy: florid duct lesion, ↑ hepatic copper | ||
Autoimmune cholangitis |
Liver biopsy: cholangitis, ductopenia | |
Chronic Hepatitis C |
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Drug-induced Hepatitis |
Clinical history: exposure to minocycline, nitrofurantoin, propylthiouracil, isoniazide, methyldopa | |
Hemochromatosis |
Genetics: C282Y, H63D mutations; Labs: ↑ Iron/Ferritin; Liver biopsy: iron overload, HII >1.9 | |
Phenotype: ZZ or MZ; Liver biopsy: hepatic inclusions, PAS + | ||
Clinical: obesity, DM, hyperlipidemia; Liver biopsy: macrosteatosis; U/S: hyperechogenicity |
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Pathogenic mechanisms unknown; Two theories: 1. Antibody-dependent cell-mediated form of cytotoxicity & 2. Cellular form of cytotoxicity
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Defect in modulation of B-cell production of IgG, creating an antigen-antibody complex on hepatocyte surface
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Autoantigen displayed on surface of antigen-presenting cells in association with HLA class II antigens
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Multiple viruses thought to trigger AIH, including HAV, HBV, HCV; Currently, the definite diagnosis requires the exclusion of viral infections
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