In the 1960s and 1970s, liver biopsy was the sine qua non for establishing the diagnoses of cirrhosis, extrahepatic biliary obstruction, and acute viral hepatitis. Those diagnoses are today generally easily established by characteristic clinical behavior; relatively specific laboratory tests, including serologic markers for hepatitis; and imaging studies, including various techniques for study of the biliary tree. As the indications for liver biopsy have changed, the practicing pathologist has become less familiar with many common disorders. The consulting pathologist to whom liver biopsies are referred may be the first to recognize histologically classic acute viral hepatitis, extrahepatic biliary obstruction, and even cirrhosis. In the last quarter century, liver transplantation has become a widely accepted and used procedure leading to increasing use of liver biopsies for various indications (1,3,6,7,13), with more and more posttransplant biopsies performed at local hospitals rather than transplant centers.
Liver biopsy is still performed for these conditions when the clinical behavior or the diagnostic procedures and test results are not typical. As an example, cirrhosis not yet expressing itself in terms of portal hypertension or impaired hepatic synthetic function can still be a clinically elusive condition and diagnosis may be established with liver biopsy performed either for a suspected liver disorder other than cirrhosis or for some entirely unrelated condition. In addition, liver biopsy serves in identifying etiologic factors, determining the stage of progression of a disease process, and evaluating the effects of therapy.
This chapter briefly reviews some of the indications for liver biopsy, with emphasis on clinical considerations. Indications for liver biopsy are as follows:
1. Abnormal liver tests not explained by other methods
a. Granulomatous hepatitis. Granulomatous hepatitis is typically diagnosed only with liver biopsy (8). Granulomas may form because of infections, such as tuberculosis, and also as a consequence of a multisystem disorder, most often sarcoidosis. Many medications, including allopurinol, isoniazid, and phenylbutazone, cause hepatic granulomas. Schistosomiasis is, worldwide, the most commonly encountered parasitic cause of granuloma. Foreign materials may reach the liver either directly during surgery or biopsy, via the bloodstream as in the case of the intravenous drug abuser, but also with inadvertent entry of foreign material after intravenous therapy, and also via the portal system from the intestines. Granulomas seen after liver transplantation can be problematic (9). Often, the cause of hepatic granulomas is not easily established. Biopsy still has an important role in providing a morphologic basis for a previously unexplained elevation of serum alkaline phosphatase and/or aminotransferases by reducing the necessity for further studies.
b. Unexplained chronic liver disease. Some patients may have chronic hepatitis but without the clinical history or serologic findings usually associated with the chronic hepatitides. Liver biopsy confirms the presence of the disorder and allows evaluation of its stage. Is there active necrosis? What is the extent of fibrosis?
c. Liver injury due to therapeutic drugs. Therapeutic drugs may cause a host of liver reactions other than granulomas (21,33), and patients may present with various signs and symptoms that mimic other liver disorders. As an example, the cardiac drug amiodarone may cause fever, elevation of aminotransferases, and malaise; in addition, clinical and histologic features identical to those of alcoholic hepatitis may be present (12).
2. Fevers of unknown origin. This application of liver biopsy has diminished in frequency because (a) some hepatotropic infections have become less common; (b) several new microbiologic and immunologic diagnostic methods have been developed; and (c) there is widespread use of increasingly sophisticated imaging procedures that allow for fine-needle aspiration (FNA) rather than core needle biopsy. Nevertheless, liver biopsy is often the way in which the diagnosis of a variety of diseases can be established. These include:
a. Mycobacterial disorders
i. Mycobacterium hominis. The number of cases of M. hominis tuberculosis has increased slightly in recent years, after having declined dramatically in the last half century.
ii. Mycobacterium avium-intracellulare. Liver biopsy is often helpful in patients with acquired immune deficiency syndrome (AIDS) who may have unexplained malaise, with or without temperature elevation (2,4,11,15,24).
b. Cytomegalovirus (CMV). CMV hepatitis is a significant risk for patients with AIDS, patients immunosuppressed after organ transplantation, and patients with immune deficiencies from other causes (29).
c. Histoplasmosis. Histoplasmosis can involve the liver as part of a disseminated infection, especially in immunodepressed patients, but may also occur as limited disease presenting with fever, elevation of serum alkaline phosphatase, with lesser elevation of transaminases. The bilirubin level is minimally elevated or normal. Generally, except in immunodepressed patients, well-formed granulomas and organisms can be demonstrated with the Gomori methenamine silver method (16).
d. Candidiasis. Although Candida lesions of the liver can be seen in immunodepressed individuals, we usually encounter it in patients with iatrogenic leukopenia, typically the leukemic patient under-going treatment. Not uncommonly, the patient has had unexplained fever for some time, and imaging techniques demonstrate multiple small hepatic and splenic lesions. Characteristic Candida organisms are found in necrotic foci, which may have relatively scant inflammatory response.
e. Toxoplasmosis. Toxoplasma gondii hepatitis is rarely seen except in newborns or in persons with AIDS or another immune disorder, although subclinical cases may occur in young adults in a manner similar to that of infectious mononucleosis. Typically, there is a mild hepatitis with extensive infiltration of the sinusoids by lymphocytes (26). Sometimes marked necrosis and granulomas are visible. The organisms are rarely demonstrable in hematoxylin-eosin-stained sections.
f. Sarcoidosis. Generally, patients present with pulmonary disease. Sometimes patients may have fever alone, however, or in association with arthralgia. Liver biopsy almost always demonstrates the characteristic noncaseating epithelioid granulomas, with or without inflammatory cell infiltration of the surrounding parenchyma (8,26).
g. Brucellosis. The diagnosis of brucellosis is considered in inverse proportion to its incidence. The liver shows nonspecific reactive changes, including mild to moderate portal inflammation and Kupffer cell hypertrophy (5,26). Necrosis of hepatocytes is uncommon and focal. In the acute phase, there may be small granulomas (5).
h. Coccidioidomycosis. Coccidioidomycosis is a fungus common to the southwestern United States, generally presenting as pulmonary disease. Rarely, an unexplained febrile illness may prompt a liver biopsy. Focal necrosis without diffuse hepatitis may be seen (26).
i. Q fever. Q fever is caused by the rickettsial agent Coxiella burnetii. In addition to unexplained fever, patients complain of headaches and have symptoms consistent with hepatitis. A distinctive but not pathognomonic “fibrin ring granuloma” is seen, with a central droplet of fat surrounded by a delicate ring of brightly eosinophilic fibrin, which is itself surrounded by an inflammatory cell aggregate consisting mostly of lymphocytes but also having some polymorphonuclear leukocytes (23). A true hepatitis with hepatocellular necrosis and both lobular and portal accumulations of chronic inflammatory cells can be seen. Similar granulomas have been reported with CMV, leishmaniasis, Epstein-Barr virus, and even hepatitis A, as well as in association with allopurinol therapy and in Hodgkin lymphoma (17,22,31).
j. Infectious mononucleosis. Rarely, hepatitis may be the presenting phenomenon. Dense accumulations of atypical lymphocytes, analogous to the Downey cells of blood smears, can be present in portal tracts and sinusoids (18,26). The infiltration may mimic acute leukemia and, rarely, may form aggregates suggestive of lymphoma. Hepatocyte necrosis is distinctly uncommon, but there may be mild cholestasis.
k. Hodgkin lymphoma. Liver biopsy is only rarely performed as a part of a staging evaluation. Involvement of the liver by Hodgkin lymphoma may resemble nonspecific portal inflammation. Noncaseating granulomas can be seen in portal tracts and involving the lobule. The classic features of Hodgkin lymphoma, especially Reed-Sternberg cells, are almost never seen.
l. Non-Hodgkin lymphoma. An abdominal lymphoma may present with fever and without peripheral nodal or thoracic disease, and liver biopsy may rarely be the first way in which the diagnosis is obtained. Alternatively, the patient with established lymphoma may have an unexplained fever, and tumor masses may not be seen with imaging techniques but may be found with liver biopsy or FNA. There has been increasing awareness of the association of hepatitis C with both intrahepatic and extrahepatic non-Hodgkin lymphoma (28).
m. Metastatic carcinoma. Metastatic carcinoma, usually confirmed with imaging or other techniques, can rarely present as fever of unknown origin without an obvious mass. In these instances, liver biopsy sometimes establishes the diagnosis.
3. Systemic inflammatory or metabolic disorders. The liver biopsy in a vasculitis may be normal or difficult to interpret unless the typical vascular lesion is serendipitously sampled. Although the term “lupoid hepatitis” was previously used for patients with autoimmune hepatitis, liver involvement is distinctly unusual in patients with true systemic lupus erythematosus (10). In contrast, liver biopsy can be especially helpful in the study of metabolic disorders, providing sufficient tissue with which appropriate biochemical and ultrastructural studies can be performed. Even in adults, liver biopsy may be the most efficacious way to diagnose certain systemic disorders, such as Gaucher disease and amyloidosis.
4. Evaluation and staging of chronic liver diseases
a. Cholestatic liver diseases
i. Chronic obstructive biliary tract disease. Liver biopsy can determine the degree of damage. In particular, biopsy can show when irrevocable damage has occurred, at which time transplantation may be a consideration.
ii. Primary biliary cirrhosis. Liver biopsy is still sine qua non for both the diagnosis and staging of primary biliary cirrhosis. Liver biopsy helps in evaluating the efficacy of new drugs and is an integral part of clinical trials.
iii. Primary sclerosing cholangitis. Primary sclerosing cholangitis is principally diagnosed with imaging studies. The changes associated with primary sclerosing cholangitis are exceedingly variable and, despite radiologically determined disease, may not be seen in a given biopsy. Indeed, the characteristic periductal “onion skin” pattern of fibrosis or the ductopenic scar may not be seen even with multiple biopsies.
iv. Chronic cholestasis. Chronic cholestasis in the absence of biliary tract disease can occur with certain drugs, chronic hepatitis, alcoholic liver disease, Hodgkin lymphoma, metastasis, and idiopathic recurrent cholestasis (30).
b. Alcoholic liver disease. Liver biopsy is no longer the principal way to study alcoholic liver disease, although sometimes it is useful in establishing the diagnosis. In alcoholics considered for liver transplantation or in posttransplantation patients with unexplained liver test results, biopsy can provide evidence of continuing alcohol use.
c. Chronic hepatitis. The liver biopsy remains the key to the evaluation of chronic hepatitis (14,19,25,29). In the patient with clinical or biochemical evidence of liver disease for more than 6 months' duration, biopsy can determine the nature of the inflammatory process, provide prognostic guidelines, and often establish etiology. The efficacy of drugs used to manage forms of chronic hepatitis can be determined. In terms of recognition of fibrosis and transition to cirrhosis (staging), biopsy remains the best approach. Although the liver biopsy is not an absolute guide to prognosis in every case, it often provides the following:
i. An indication of the severity of the lesion at a given time, including the amount of inflammation and the degree and distribution of necrosis.
ii. Some information about cause, or at least exclusion of some etiologic factors.
iii. Information about irreversible architectural alterations, such as fibrosis to septum formation to cirrhosis.
iv. Recognition of incidental lesions.
d. Cirrhosis. Cirrhosis is a pathophysiologic alteration of the liver with both vascular septa, connecting portal and central venous systems, and regenerative nodules. This combination, septa plus nodules, is the basis of the signs and symptoms we recognize as cirrhosis (portal hypertension, decreasing catabolic function, and decreasing synthetic function).
Liver biopsy is useful for four principal reasons: (a) to confirm the clinical impression of cirrhosis where the diagnosis is not unequivocal (20,26); (b) to ascertain the cause of the injury; (c) to attempt to determine prognosis; and (d) to identify patients in whom clinical manifestations of cirrhosis are simulated, but in whom there may be some other condition, such as nodular hyperplasia or schistosomiasis. In addition, (e) the biopsy can document hepatocellular dysplasia and/or carcinoma.
The histopathologic diagnosis of cirrhosis is not always straightforward (20,26). The appreciation of nodule formation and, consequently, the diagnosis of cirrhosis by liver biopsy can be quite difficult, particularly if the sample obtained is suboptimal. Overdiagnosis can also occur, especially when cirrhosis is diagnosed (a) on the basis of fibrosis alone, (b) in the face of intact acinar architecture and without regenerative nodule formation, (c) when recent bridging necrosis is thought to be fibrosis, or (d) when capsular fibrosis appears to be intraparenchymal because of the way in which the tissue is oriented in histologic sections. This latter problem is particularly prevalent during examination of wedge biopsies of the liver, without obtaining deep parenchyma relatively far from the capsule.
The clinician should consider several useful features and concepts when establishing the diagnosis of cirrhosis:
i. The liver tends to be hard or gritty when the needle enters.
ii. Fragmentation is common in cirrhosis. Depending on the operator's technique, however, it may also occur with relatively normal liver and should not be regarded as diagnostic.
iii. Capsular fibrosis can simulate a septum. Evidence of regeneration should be sought if the putative septum is histologically close to the capsule.
iv. Reticulin stain is particularly useful. Two-cell-thick liver plates of the regenerative nodule are well shown with reticulin. In fragmented specimens, isolated nodules often are circumscribed by reticulin fibers.
v. Elastic stains, including Victoria blue and orcein, can be useful in distinguishing elastic-rich septa of cirrhosis from elasticpoor capsular tissue.
e. Candidates for liver transplantation. Evaluation of the liver biopsy is not required before liver transplantation. Most chronic liver disease patients will be selected for transplantation because of clinical evidence of increasing liver function deterioration. In acute liver failure, liver biopsy may be contraindicated.
The donor liver may be evaluated to determine if conditions exist that may affect graft survival, such as excess steatosis.
5. Evaluation of liver injury caused by therapeutic drugs. It is not possible in this brief review to discuss in detail the responses of the liver to therapeutic agents (33). The changes seen, either individually or in combination, include (a) steatosis and other cellular degenerative changes, (b) cholestasis, (c) lobular hepatitis, (d) chronic active hepatitis, (e) granulomatous hepatitis, (f) fulminant (massive) hepatitis, (g) destructive cholangitis, (h) sinusoidal dilatation, (i) veno-occlusive disease, (j) Budd-Chiari syndrome, (k) cirrhosis, (l) hepatocellular proliferation and hepatocellular neoplasia, and (m) nonhepatocellular neoplasia, such as that associated with angiosarcoma.
6. Diagnosis of space-occupying lesions. This is a traditional application for the liver biopsy and remains useful today. The FNA technique can often provide the diagnosis and spare the patient the slightly more traumatic biopsy. Core biopsy provides sufficient tissue for immunohistochemical studies conducted to determine the site of origin of an unknown primary.
The core needle biopsy can also show changes of the uninvolved liver that reflect the presence of a mass lesion. Specimens from the vicinity of a mass typically show portal edema, proliferation of bile ductules, and infiltration by neutrophils, with focal and irregular sinusoidal dilatation. Changes are similar to those seen in extrahepatic biliary obstruction but are generally not accompanied by the characteristic clinical findings of biliary obstruction.
7. Unexplained hepatomegaly and/or mild hepatic dysfunction. The two most common findings when liver biopsy is performed for hepatomegaly, with or without mild liver dysfunction, are nonspecific steatosis and congestion. Usually these findings are not clinically helpful.
a. Hepatocellular and/or pleomorphic hypertrophy may be seen as a nonspecific response to various medications. There is an increase in the amount of cytoplasm in the zone 3 (centrolobular) hepatocytes. The liver cells may resemble the “ground-glass” cells of hepatitis B carriers, but these “induction cells” do not react with Victoria blue, orcein, or monoclonal antibody to hepatitis B surface antigen.
b. Congestion as an unexpected finding is most often caused by mild congestive heart failure. In some cases, however, congestion may be an early indication of venous outflow obstruction, as in early Budd-Chiari syndrome. The correct diagnosis may not be evident until the condition progresses and, even in retrospect, may not be apparent prior to the development of the characteristic zone 3 atrophy.
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