Autoimmune Hepatitis

Published on 09/08/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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(Left) Venous phase CT shows heterogeneous liver parenchyma with evidence of periportal edema

, a nonspecific sign often seen in acute hepatitis, among other causes.

(Right) CT section in the same case shows subcapsular and peripheral wedge-shaped foci of hyperdensity , representing confluent fibrosis and is usually seen in advanced and more chronic liver damage. Liver biopsy showed acute and advanced liver injury due to autoimmune hepatitis (AIH).

(Left) Axial CECT of an autoimmune hepatitis-primary sclerosing cholangitis (AIH-PSC) overlap shows a nodular, cirrhotic liver with signs of portal hypertension, including splenomegaly, ascites, and varices . The intrahepatic ducts are dilated with an abnormal arborization, suggestive of PSC.

(Right) Axial CECT in the same patient shows dysmorphic liver, ascites, varices, and dilated, irregular intrahepatic bile ducts typical of primary sclerosing cholangitis.

TERMINOLOGY

Abbreviations

• Autoimmune hepatitis (AIH)

Synonyms

• Chronic active hepatitis

Definitions

• Chronic hepatitis of unknown etiology characterized by hyperglobulinemia, circulating autoantibodies, and inflammatory changes on hepatic histology

IMAGING

General Features

• Best diagnostic clue

Dysmorphic liver with prominent periportal fibrosis ± signs of portal hypertension ± irregular intrahepatic ductal dilation

– Widened fissures, deep gallbladder fossa, ↑ caudate:right lobe ratio

Radiographic Findings

• AIH is not diagnosed specifically by imaging criteria

CT Findings

• CECT

Typical signs of cirrhosis + portal hypertension

Bands of fibrosis may show persistent, increased, delayed enhancement

Irregular dilation of intrahepatic ducts in autoimmune hepatitis-primary sclerosing cholangitis (AIH-PSC) overlap disease

MR Findings

• Signs of cirrhosis ± portal hypertension

• MRCP is best for detecting irregular dilation of intrahepatic ducts in AIH-PSC overlap disease

Imaging Recommendations

• Best imaging tool

MR with MRCP

DIFFERENTIAL DIAGNOSIS

Primary Biliary Cirrhosis (PBC)

• Imaging and other features may simulate or coexist with AIH: AIH-PBC overlap disease

• PBC typically affects middle-aged women

• Leads to early cholestatic injury (pruritus + jaundice)

• Imaging: Prominent regenerative nodules, lace-like fibrosis, large perihepatic lymph nodes

Primary Sclerosing Cholangitis (PSC)

• Imaging and clinical features may simulate or coexist with AIH: AIH-PBC overlap disease

• Often associated with ulcerative colitis

• Irregular dilation and arborization of bile ducts with thickened walls

Viral Hepatitis

• Imaging and clinical features may be identical to AIH

• Differentiation relies on serologic testing and evidence of viral antigens ± antibodies

Alcoholic Hepatitis

• Imaging evidence of steatosis

• History of alcohol use, biopsy evidence of steatosis, hepatocyte inflammation, and necrosis

PATHOLOGY

Staging, Grading, & Classification

• May exist as classic or typical form (type 1 AIH)

Accounts for ∼ 80% of AIH cases in USA

Lab tests

– ↑ serum alanine aminotransferase (> 5x upper limit of normal)

– Immunoglobulin G (IgG) > 2x normal

– + anti smooth muscle antibodies

– + antinuclear antibodies (ANA)

• Type 2 AIH

Antibodies to liver and kidney microsomes

Usually diagnosed in childhood

40% have other autoimmune diseases

• “Overlap” or “variant” syndromes

Clinical and serologic features of other autoimmune diseases (20% of all patients with AIH)

– PBC

– PSC

– Autoimmune cholangitis

AIH-primary biliary cirrhosis overlap

– Histologic features of AIH

– Serologic features of PBC

Antimitochondrial antibodies (AMA)

– Histologic features of PBC but absent AMA

May have antinuclear antibodies or smooth muscle antibodies

Sometimes referred to as autoimmune cholangiopathy, autoimmune cholangitis, “AMA-negative PBC”

AIH-primary sclerosing cholangitis overlap

– Serologic features of AIH but cholangiographic abnormalities characteristic of PSC

– Overlap prevalence may be 1-10% of all patients with AIH

– Affected patients have more cholestatic symptoms, laboratory and histologic findings than those with typical AIH

↑ alkaline phosphatase (2x normal)

Pruritus, jaundice

– May have other autoimmune diseases

Ulcerative colitis

Diabetes mellitus

Polyglandular autoimmune disease

Thyroiditis

Addison disease (adrenal insufficiency)

Systemic lupus, rheumatoid arthritis

Glomerulonephritis, etc.

Gross Pathologic & Surgical Features

• Moderate to severe lobular hepatic inflammation

• Advanced disease leads to cirrhosis

Bridging fibrosis, cellular necrosis, regenerative nodules

Microscopic Features

• Histologic features alone are not diagnostic of AIH

• Lymphocytic, often lymphoplasmacytic inflammatory infiltrates extending from portal tracts into parenchyma

• Often associated with hepatocyte injury

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

May be asymptomatic

– Diagnosed only after detecting abnormal liver function

Heterogeneous and fluctuating course

Marked variability in clinical manifestations

May have long indolent periods

– Or rapid progression to acute liver failure

Usually following indolent and undiagnosed period

More advanced disease

– Pruritus, jaundice

– Fatigue, abdominal discomfort

– Nausea, vomiting

• Other signs/symptoms

After progression to cirrhosis

– Abdominal distention (ascites), variceal bleeding

• Diagnosis is based on several factors

Exclusion of viral, alcoholic, or toxic hepatic injury

Exclusion of genetic disease (e.g., α-1-antitrypsin deficiency)

Marked elevation of serum aminotransferase + immunoglobulins

Autoantibodies (e.g., antinuclear, anti-smooth muscle)

Histology: Periportal &/or panlobular lymphoplasmacytic hepatitis

Demographics

• Age

Occurs in children and adults of all ages

– Onset usually occurs by age 40 years

– Patients with later presentation often have evidence of chronic liver injury

25% have cirrhosis at time of initial diagnosis

• Gender

Predominantly affects women (∼ 70%)

Natural History & Prognosis

• Most patients respond to immunosuppressive therapy

Others progress to chronic injury with cirrhosis

Treatment

• Azathioprine, prednisone

• Sympathomimetic amines (e.g., dextroamphetamine sulfate)

DIAGNOSTIC CHECKLIST

Consider

• Role of imaging is to detect signs of acute or chronic liver injury, portal hypertension, associated abnormalities (e.g., biliary ductal disease)

Hematoxylin and eosin stain shows prominent lobular inflammatory cell infiltrates with large numbers of plasma cells in a case of autoimmune hepatitis. (Courtesy L. Yerian, MD.)

Axial CECT in a patient with autoimmune hepatitis shows a heterogeneous liver parenchyma and periportal edema , with subcapsular + parenchymal hyperdense bands that represent fibrosis.

Axial CECT in the same patient shows peripheral fibrosis with retraction of the overlying hepatic capsule , a finding usually associated with confluent fibrosis & indicative of chronic liver injury. Also note the widened fissures , typical of cirrhosis but not specific for AIH.

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(Left) Venous phase CT shows heterogeneous liver parenchyma with evidence of periportal edema

, a nonspecific sign often seen in acute hepatitis, among other causes.