Autoimmune hepatitis

Autoimmune hepatitis
Diagnosis in short
Autoimmune hepatitis. H&E stain.
LM	interface hepatitis with plasma cells, +/- bile duct injury
LM DDx	viral hepatitis, primary biliary cirrhosis, AIH-PBC overlap, drug reaction
Site	liver
Blood work	ANA +ve, IgG elevated, LKM-1 +ve, SMA +ve, HBV -ve, HCV -ve, HIV -ve
Clin. DDx	primary biliary cirrhosis, primary sclerosing cholangitis

Autoimmune hepatitis, abbreviated AIH, in an uncommon medical liver disease that occurs in adults and children.

General

• Several criteria exist to diagnose and histology (alone) is not sufficient.

Diagnosis

Simplifed diagnostic criteria (2008):

1. Antibody titer.
2. Elevated IgG.
3. Liver pathology.
4. Exclusion of viral hepatitis.

Details (scoring):

Finding	Score
ANA or SMA 1:40	1 point
ANA or SMA 1:80	2 points
LKM-1 1:40	2 points
IgG upper normal	1 point
IgG 1.1x upper limit	2 points
Histology compatible	1 point
Typical AIH histo.	2 points
No viral hepatitis	2 points

Interpretation: Definite >= 7 points. Probable = 6 points.

Notes:

• Autoantibodies may be seen in HCV.
• A normal IgG is very unusual in AIH - but may be seen in atypical variants with zone III involvment.

Abbreviations:

• ANA = anti-nuclear antibody.
• SMA = smooth muscle antibody.
• LKM-1 = liver kidney microsomal type 1 antibody.

Treatment

• Immunosuppresants (prednisone, azathioprine).

Microscopic

Classification:

• Typical:
  • Interface hepatitis (zone 1).
    • Lymphoplasmacytic infiltration of portal tracts / lobule.
      • Periportal plasma cells - key feature.
  • Emperipolesis - one cell penetrates into another one (uncommon finding).
  • Hepatic rosette - inflammatory cells around reactive hepatocytes.
• Compatible:
  • Chronic hepatitis - lymphocytic dominant.
• Atypical:
  • Signs of an other disease.

Notes:

• PAS stain may be useful - find plasma cells.
  • Lots of plasma cells should prompt consideration of AIH.
• Atypical Autoimmune hepatitis may have zone III involvment (lymphoplasmacytic infiltrate) and a normal IgG.

Images

• 

  AIH - low mag. (WC)

• 

  AIH - intermed. mag. (WC)

• 

  AIH - cropped - very high mag (WC)

www:

• AIH (jpma.org.pk).

Emperipolesis:

• Emperipolesis (ajronline.org).
• Emperipolesis (ouhsc.edu).

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LIVER, RIGHT LOBE, CORE BIOPSY:
- LIVER WITH INTERFACE HEPATITIS (GRADE 2/4) WITH PLASMA CELLS.
- MODERATE FIBROSIS (STAGE 2/4).

COMMENT:
The histologic findings are compatible with autoimmune hepatitis.  Serologic findings (ANA
positive, IgG positive, viral serology negative) are noted.  Correlation with LKM-1
serology is suggested, if not done.

The histology is not suggestive of primary biliary cirrhosis.

Micro

The sections show two cores of liver with an interface hepatitis with plasma cells.
Numerous eosinophils are seen focally in the portal tract. The number of ducts is 
focally increased in several portal tracts and associated with neutrophils 
(ductular reaction).

Size of biopsy: adequate.
Fragmentation: absent.
Fibrosis: Stage 2/4.
Fibrous septa: present.
Septa with curved contours: present, focally only.
Large droplet steatosis (% of hepatocytes): minimal <5%.
Ballooning of hepatocytes: absent.
Mallory-Denk bodies: absent.
Portal inflammation: present (1/4).
Interface activity: mild (1/4).
Lobular necroinflammation: not identified.
Ducts: numbers within normal limits.
Duct injury: present.
Ductular reaction: present.
Cholestasis: not apparent.
Terminal hepatic venules: present.
Iron stain: absent.
Ground glass cells with routine stains: absent.

See also

• Medical liver disease.