Liver Histopathology

Explain the role of liver biopsy.

• Diagnosis: The biopsy is particularly useful in patients with atypical clinical features and coexisting disorders such as steatosis and hepatitis C virus. Indications include abnormal liver tests of unknown cause, multiple parenchymal diseases, fever of unknown cause, and focal and diffuse abnormalities on an imaging study indicating conditions such as amyloidosis or granulomatous diseases.

• Prognosis: Assessing fibrosis to predict prognosis is of particular importance in assessing risk of complications, including hepatocellular carcinoma (HCC).

• Treatment: Develop treatment plans based on histologic analysis. For example, liver biopsy is often obtained to ascertain control of inflammation prior to steroid dose reduction or discontinuation of immunosuppression therapy for autoimmune hepatitis.

What kind of prebiopsy testing and management of medication are necessary before liver biopsy?

• Measurement of complete blood count, including platelet count, prothrombin time, and international normalized ratio.

• Antiplatelet medication should be discontinued 7 to 10 days prior to biopsy. Warfarin should be discontinued at least 5 days prior to liver biopsy.

What are contraindications for liver biopsy?

• Absolute: Uncooperative patient, severe coagulopathy, infection of hepatic bed, extrahepatic bile obstruction

• Relative: Ascites, morbid obesity, possible vascular lesion, amyloidosis, hydatid disease

Describe adequacy of the liver biopsy.

The adequate portal tract number is more than 11, and the minimal requirement is more than 5 portal tracts. The grading and staging accuracy is reduced in biopsies less than 2.0 cm in length. Although a 1.5-cm biopsy specimen may be adequate for assessing many liver diseases, a short specimen may result in a failure to recognize cirrhosis up to 20%.

Describe the normal histology of liver.

See Figure 32-1 .

What kinds of changes can you see as evidence of hepatocytes injury in the liver?

• Acidophil body (Councilman body): Dr. Councilman described acidophil bodies in a yellow fever patient for the first time. Hepatocytes show acidophilic cytoplasm and nucleus are pyknotic or apoptotic. Causes include viral hepatitis, drugs, toxins, and steatohepatitis ( Figure 32-2 A ).

  

• Balloon cell degeneration: The cytokeratin forms a filamentous support network within hepatocytes. Injury of intermediate filaments in hepatocytes creates swelling and increases in volume with wisps of cytoplasmic material. Causes include steatohepatitis, acute hepatitis, and ischemia (see Figure 32-2 B ).

• Mallory-Denk body (Mallory hyaline): Irregular ropelike eosinophilic intracytoplasmic strings represent aggregates of cytokeratin intermediate filaments (cytokeratin 8 and 18). Causes include steatohepatitis, drugs (amiodarone, etc.), chronic cholestasis, and Wilson disease (see Figure 32-2 B ).

• Feathery degeneration: Hepatocyte injury is due to bile salt. Hepatocytes show reticular cytoplasm (see Figure 32-2 C ).

What histologic patterns of liver cell necrosis are seen?

• Single cell necrosis

• Interface activity (piecemeal necrosis): Necrosis of individual hepatocytes at the limiting plate results in portal and periportal fibrosis. Causes include viral hepatitis, autoimmune hepatitis, and drugs ( Figure 32-3 A ).

  

• Zonal necrosis: Zone 3 necrosis (centrilobular necrosis) is seen in ischemia and drugs (acetaminophen) (see Figure 32-3 B ).

• Bridging necrosis: Causes for necrosis between central-to-central and portal-to-portal include severe autoimmune hepatitis, ischemia, viruses, and drugs. It results in significant fibrosis and cirrhosis.

What kind of abnormal material can accumulate in cytoplasm of hepatocytes and what is the cause?

• Steatosis: Accumulation of lipids, primarily triglycerides, in hepatocytes. Normally steatosis is seen in less than 5% of hepatocytes. Causes include ethanol, obesity, diabetes, and drugs ( Figure 32-4 A ).

  

• Iron: Causes include hemochromatosis, frequent transfusions, and hemolysis (see Figure 32-4 B ).

• Copper: Causes include Wilson disease, and chronic cholestasis because bile is the single excretion route for copper.

• α1-Antitrypsin globules: Accumulation of abnormal protein. Periodic acid–Schiff (PAS)– and periodic acid–Schiff–diastase (PASD)–positive cytoplasmic globules are present in zone 1 hepatocytes (see Figure 32-4 C ).

• Ground-glass hepatocytes: The cause is a viral particle of hepatitis B virus, only seen in chronic hepatitis (see Figure 32-4 D ).

What kinds of inflammatory cells can be seen in liver biopsy, and what kinds of etiologic factors are suspected?

• Neutrophils: Steatohepatitis (alcoholic and nonalcoholic), surgical hepatitis (margination of neutrophil during surgery), drug toxicity

• Eosinophils: Drug toxicity, parasitic infection, autoimmune hepatitis

• Plasma cells: Autoimmune hepatitis

• Lymphocytes: Viral hepatitis, drugs

What kind of pigment can be seen in the liver?

• Hemosiderin: Golden brown pigment seen in zone 1, red cell degeneration remnants

• Lipofuscin: Brown granules seen in zone 3; “wear and tear” pigment, commonly seen in older adult patients; increased lysosomal activity

• Bile: Green-yellow pigment seen in zone 3; bile is not present in normal liver

What kinds of nuclear inclusions can be seen in hepatocytes?

• Glycogenated nuclei: Glycogen accumulation is seen. Causes include steatohepatitis, diabetes, and Wilson disease ( Figure 32-5 A ).

  

• Cytomegalovirus: Owl’s eye intranuclear inclusion is seen (see Figure 32-5 B ).

• Herpes simplex: Multinucleated cells with intranuclear inclusions are diagnostic (see Figure 32-5 C ).

• Hepatitis D virus: Sanded nuclear inclusion is seen. Hepatitis D is a coinfection with hepatitis B.

• Adenovirus: Smudgy inclusions are seen.

What kinds of special stains are commonly used for liver biopsy?

• Masson trichrome stain highlights fibrosis.

• Reticulin stain highlights hepatic plates and is useful to evaluate alteration in hepatic architecture such as massive hepatocyte necrosis and loss of reticulin framework in HCC.

• PAS stain highlights glycogen in hepatocytes and α1-antitrypsin globules in periportal hepatocytes. When PASD stain is used, the glycogen has been removed by diastase, and the only positive staining globules are α1-antitrypsin globules.

• Perls’ iron stain shows distribution and amount of iron overload.

• Rhodamine stain detects copper accumulation.

• Congo red stain detects amyloid.

• Oil red O confirms microvesicular steatosis. Fresh tissue is required, and it is useful for the diagnosis of acute fatty liver of pregnancy.

What is the difference between fatty liver and steatohepatitis?

Steatosis indicates accumulation of lipid in hepatocytes. Steatohepatitis refers to a histologic constellation of findings with evidence of additional modes of hepatocyte injury such as ballooning degeneration, Mallory-Denk bodies, or necroinflammation.

What are macrovesicular steatosis and microvesicular steatosis (see Figure 32-4A )?

• Macrovesicular: The hepatocytes are distended with a single droplet, which displaces the nucleus.

• Microvesicular: The hepatocytes are filled with small droplets, but the nucleus is centrally located.

Can histologic examination distinguish between alcoholic hepatitis and nonalcoholic hepatitis?

Not really. Alcoholic hepatitis shows more neutrophils and Mallory hyaline, and occasionally distinction between the two is possible.

How does scarring progress with steatohepatitis ( Figure 32-6 )?

Fibrosis starts from pericentral vein with delicate chicken-wire–like fibrosis along the sinusoids. On the other hand, the progression of viral hepatitis starts from portal tracts.

How is nonalcoholic steatohepatitis (NASH) graded?

Because disease process including necroinflammatory response, type of hepatocyte injury and fibrosis are distinctly different between steatohepatitis and viral hepatitis, two systems, the Brunt system and the NASH Clinical Research Network (CRN) scoring system, were developed to assess activity and fibrosis particularly for NASH. Grade is based on degree of steatosis, hepatocellular ballooning, and lobular inflammation. CRN was developed to include both adult and pediatric population.

What histologic features are typical of chronic hepatitis?

Chronic hepatitis is a necroinflammatory process in which hepatocytes rather than bile ducts are predominantly injured. Inflammatory cells are composed of lymphocytes and plasma cells, and inflammation is predominantly in the portal tracts with evidence of interface activity. Viral hepatitis, autoimmune hepatitis, Wilson disease, and α1-antitrypsin disease show the chronic hepatitis pattern.

What histologic features are seen in autoimmune hepatitis?

Histologic features of autoimmune hepatitis can be variable. Classic histologic findings include portal and lobular chronic inflammation with plasma cell–dominant interface activity associated with spotty necrosis. Hepatic rosette formation and bridging necrosis may be seen. Variants include cases without plasma cell dominance, acute hepatitis, and unexpected cirrhosis.

What histologic features are seen in chronic hepatitis C?

Lymphoid aggregates and mild to moderate interface activity are present. The lobular activity is mild and consists of spotty necrosis with 1 to 2 mononuclear cells and acidophil bodies. Bile ducts may show lymphocytic infiltrate.

What histologic features are seen in chronic hepatitis B?

Chronic hepatitis B may show ground-glass hepatocytes, which reflects accumulation of hepatitis B antigen within the endoplasmic reticulum of the hepatocytes.

What is the goal for grading and staging systems for chronic hepatitis and what kinds of systems are there?

The goal is to ensure the same lesions are being evaluated and given similar diagnostic weight regardless of the observers. Various systems (Kendoll histologic activity index (HAI) score, Ishak modified HAI score, Scheuer system, Metavir system, and Batts and Ludwig) are available, but all assessments are based on portal chronic inflammation, interface activity, lobular necroinflammatory lesion, and fibrosis.

How is chronic hepatitis graded and staged?

The Batts and Ludwig system is the simplest system and is widely used.

• Grading of inflammatory activity:

  • Grade 1 (Minimal activity): Mild portal inflammation, but scant interface activity and no lobular necrosis

  • Grade 2 (Mild activity): Mild portal inflammation, interface activity, and scant lobular necrosis

  • Grade 3 (Moderate activity): Moderate portal inflammation, interface activity, and lobular spotty necrosis

  • Grade 4 (Severe activity): Marked portal inflammation, brisk interface activity, considerable spotty necrosis, and area of confluent necrosis

• Staging of fibrosis:

  • Stage 1 (Portal fibrosis): Fibrous portal expansion

  • Stage 2 (Periportal fibrosis): Periportal or rare portal-portal septa

  • Stage 3 (Septal/bridging fibrosis): Fibrous septa with architectural distortion

  • Stage 4 (Cirrhosis): Cirrhosis