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a.Clinical presentation. There may be no symptoms or physical findings.

1.Approximately 25% of patients have a palpable abdominal mass or abdominal pain.

2.Up to 30% of patients present with spontaneous rupture and hemorrhage into the peritoneal cavity. The mortality rate for rupture is about 9%.

b.Pathology. Adenomas are soft tumors with sharply circumscribed edges but no true capsule. Histologically, only normal hepatocytes are present, and there is no evidence of malignancy.

c.Diagnosis

1.The tumor is usually suspected when a mass is seen on ultrasound or other scan of the liver.

2.MRI with gadolinium enhancement is the diagnostic procedure of choice because it can often differentiate adenomas from focal nodular hyperplasia or malignant lesions.

3.Arteriograms are rarely used anymore.

4.Liver function studies are generally normal.

5.Biopsy is needed to exclude malignancy.

d.Treatment

1.Oral contraceptives, anabolic steroids, and pregnancy should be avoided, as in the absence of these, the tumor can regress. If the diagnosis is confirmed and the lesion is small, intrahepatic, and associated with oral contraceptive use, it may be safely observed.

2.Occasionally, the tumor is exophytic on a narrow pedicle and can be easily excised.

3.If the tumor is large and superficial or if a woman anticipates pregnancy in the near future, it should be resected because of the risk of spontaneous rupture and hemorrhage.

4.In cases of spontaneous rupture with hemorrhage into the peritoneal cavity, the patient should initially be resuscitated. If it is recognized that this patient has a ruptured adenoma and is hemodynamically stable, the bleeding can be successfully managed by identifying the bleeding vessel with angiography and embolizing it with thrombus. If angiography is not immediately available, if the patient remains unstable, or if a hepatic adenoma or other hepatic tumor is not suspected, the patient should be taken to the operating room.

a.The recommended procedure is hepatic artery ligation. This frequently controls the bleeding and is associated with only minor aberrations in liver function when the liver is not cirrhotic.

b.Hepatic resection in the presence of acute rupture has a high mortality rate. Elective resection should, however, be performed at a later date.

c.If the patient is very unstable after rupture despite major resuscitative efforts, open packing or angiographic embolization of the hepatic artery may control the hemorrhage.

5.Although the risk of carcinoma developing in this adenoma is low, there are several case reports of this progression. If not excised, adenomas should be followed indefinitely for significant growth or other changes.

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3.Focal nodular hyperplasia (FNH) is the third most common benign liver tumor. It occurs most often in women and has a weak association with oral contraceptive use.

a.Clinical presentation. Symptoms and physical findings, when they occur, are similar to those seen with hepatocellular adenoma; however, FNH is usually asymptomatic and discovered as an incidental finding. Spontaneous rupture is rare.

b.Pathology. Single or multiple lesions with a nodular appearance externally and a central scar with radiating septa on cut section are seen.

c.Histology. The tumors contain all hepatic elements and are composed of hyperplastic hepatocytes with inflammatory (Kupfer) cells. Bile duct epithelium is a prominent finding in contrast to hepatocellular adenoma.

Overall, the lesions resemble regenerating nodules of cirrhosis.

d.Diagnosis and treatment are similar to those for hepatocellular adenoma. The Kupfer cells in FNH take up the sulfur colliod in the sulfur-colloid scan, and the lesion appears indistinguishable from normal liver parenchyma. In contrast, adenomas contain no Kupfer cells and would appear as a filling defect. For this reason, the sulfur colloid scan can be a valuable adjunct to differentiate these two lesions that commonly present in the same patient population.

4.Infantile hemangioendothelioma is a benign liver tumor of children that has malignant potential.

a.Clinical presentation. It may present as hepatomegaly and high-output cardiac failure in an infant with a large arteriovenous fistula.

b.Pathology. Grossly, it is a nodular lesion, and microscopically, it shows dilated vascular spaces lined by endothelium.

c.Treatment is by excision or hepatic artery ligation.

D

Primary malignant tumors of the liver account for 0.7% of all cancers. In men, 90% of primary liver tumors are malignant; in women, only about 40% are malignant.

1.Hepatocellular carcinoma (hepatoma) is the most common primary malignant liver tumor.

a.Incidence of hepatocellular carcinoma varies geographically, being highest in Africa and Asia and lowest in the Western world.

1.Men are affected twice as often as women.

2.The average age of affected individuals is 50 years, but hepatocellular carcinoma can occur at any age.

b.Associations. The tumor shows an association with a number of pre-existing diseases and environmental substances, such as:

1.Chronic hepatitis B virus (HBV) infection (present in as many as 80% of cases worldwide). The risk of developing hepatocellular carcinoma is increased 200-fold for chronic HBV carriers. The risk in male carriers is as high as 50%. Hepatocellular carcinoma is associated with chronic hepatitis C infection.

2.Cirrhosis, regardless of etiology (present in approximately 60%–90% of patients), especially macronodular cirrhosis

3.Hemochromatosis with iron overload and cirrhosis

4.Schistosomiasis and other parasitic infestations

5.Environmental carcinogens

a.Industrial substances, including polychlorinated biphenyls; chlorinated hydrocarbon solvents, such as carbon tetrachloride; nitrosamines; vinyl chloride and polyvinyl chloride; and organochloride pesticides

b.Organic materials, including aflatoxins (produced by Aspergillus flavus or A. fumigatus and found on foods, such as peanuts)

c.Thorotrast, an intravenous contrast agent that is no longer used

c.Clinical presentation

1.Smaller hepatocellular carcinomas are usually asymptomatic. Larger and more advanced tumors often present as a dull, aching pain in the right upper quadrant; malaise, fever, and jaundice may also be present.

2.Physical examination reveals hepatomegaly (present in 88% of cases), weight loss (in 85%), a tender abdominal mass (in 50%), or findings associated with cirrhosis (60%).

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3.About 10%–15% of patients present with acute hemorrhage into the peritoneal cavity with resultant shock.

4.Paraneoplastic syndromes also may occur in which tumor cells secrete hormonelike substances that cause unusual syndromes, such as Cushing's syndrome.

d.Diagnosis. Liver function test results are usually abnormal, but there is no particular diagnostic pattern.

1.Alpha-fetoprotein, a protein made by embryonal hepatocytes, is elevated in 70% of cases.

2.Hepatic ultrasound, CT scan, and MRI are the most reliable and commonly used studies for determining the presence and operability of the lesions. These studies are positive in up to 90% of cases. Smaller lesions require CT or MRI with intravenous contrast enhancement because they will only be evident in the arterial phase. Ultrasound is not an adequate modality to assess lesions <2 cm.

e.Pathology. Hepatocellular carcinoma occurs as a solitary mass or as multiple masses. Local invasion, especially into the diaphragm, is common, as are distant metastases with the lung being most commonly involved (in up to 45% of cases).

f.Surgical treatment includes resection and transplantation. To catch tumors early and increase the potential for cure, high-risk individuals (e.g., those with chronic HBV or those with cirrhosis) should be screened every 6 months with imaging studies and measurement of alpha-fetoprotein.

1.If lesions are resectable, the average survival is 3–4 years, and 5-year survival rate can now be achieved in 40% of patients.

2.The operative mortality rate is approximately 5% but is significantly higher in patients with coexistent cirrhosis.

3.If lesions are unresectable, and transplantation is not an option, patients have a mean survival time of 4 months.

4.Attempts to induce tumor necrosis by hepatic artery ligation have shown poor results.

g.Chemotherapy has been ineffective when given systemically, but administration of drugs into the hepatic artery has given some promising preliminary results.

h.Combination therapy using chemoembolization and local ablation may be palliative for patients with unresectable lesions. Chemoembolization is the technique of embolizing the arterial supply of the tumor with chemotherapeutic agents mixed with thrombus. Ablative therapies include instillation of absolute ethanol into the lesion or insertion of a probe and delivery of radio frequency energy into the lesion. Both chemoembolization and local ablation cause local necrosis of the tumor, and the combination may improve survival.

2.Hepatoblastoma

a.Clinical presentation. Hepatoblastoma is the most common primary malignant liver tumor in children and presents with abdominal distention, failure to thrive, and other symptoms of liver failure. Alpha-fetoprotein is frequently positive.

b.Pathology. Approximately 80% are solitary liver masses that microscopically show nests and cords of primitive cells, resembling embryonic hepatocytes.

c.Treatment is surgical excision. Inoperable tumors are treated with irradiation or chemotherapy but with poor results.

3.Cholangiocarcinoma is a tumor that arises from the bile duct epithelium; it represents 5%–30% of all primary hepatic malignancies.

a.Clinical presentation. Signs and symptoms include right upper quadrant pain, jaundice, hepatomegaly, and occasionally a palpable mass. Patients are usually 60–70 years of age.

b.Pathology. A hard grayish mass is found that microscopically shows adenocarcinoma of the biliary epithelium. Metastasis occurs initially to the regional lymph nodes or to the liver.

c.Etiology. Associated conditions include parasitic infections (e.g., Clonorchis sinensis), primary sclerosing

cholangitis, or Thorotrast exposure.

d.Treatment of intrahepatic tumors is resection when feasible. Overall survival is poor.

4.Angiosarcoma, or malignant hemangioendothelioma, is a highly malignant liver tumor composed of irregular spindle cells lining the lumina of hepatic vascular spaces.

a.Etiology. Most cases (85%) occur in men, and there is a high association with chemical agents, especially vinyl chloride, Thorotrast, arsenicals, and organochloride pesticides.

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b.Clinical presentation. The tumor commonly spreads locally to the spleen (80% of cases) and distantly to the lungs (60% of cases).

c.Treatment is resection when feasible, but patients rarely survive 1 year.

5.Sarcomas other than angiosarcoma are rare but are highly malignant and frequently not curable.

E

Metastatic tumors of the liver are much more common than primary tumors (ratio 20:1).

1.Overview. The liver is the second most common site of metastasis (exceeded only by regional lymph nodes) for all primary cancers of the abdominal viscera. Over two thirds of all colorectal cancers ultimately involve the liver, and up to 50% of cancers outside the abdomen metastasize to the liver. Fully one third of all cancers ultimately spread to the liver, which is the most common site of hematogenous spread.

2.Diagnosis may be difficult because liver metastases are often asymptomatic.

a.Laboratory studies. In a recent National Cancer Institute study, no single laboratory blood test could predict liver metastases in more than 65% of patients with subclinical disease. This percentage can only be increased by using imaging techniques.

1.Liver function studies (e.g., aspartate transaminase or alkaline phosphatase) detect only 50%–65% of subclinical metastases.

2.Testing for carcinoembryonic antigen has been valuable for predicting the presence of liver metastasis in colorectal cancer because it is positive in over 85% of patients with proven disease. Unfortunately, this test lacks specificity.

b.Imaging techniques are expensive screening tests but are currently the most reliable nonsurgical method of finding liver metastases.

1.CT scans and MRIs are the most accurate imaging techniques but are expensive screening tests.

2.Ultrasonography is almost as reliable as CT and MRI, and it provides a reasonable screening test.

3.Treatment for metastatic disease to the liver depends on the type of primary tumor. Because colorectal cancer has generated the most reliable statistics, those figures are cited here.

a.Chemotherapy for liver metastasis from colorectal cancer has been disappointing.

1.Systemic 5-fluorouracil therapy has resulted in a response rate of 9%–33% and a median survival of 30– 60 weeks. (A response is defined as a 50% decrease in the size of an existing tumor and the development of no new lesion for a period of 1–2 months.)

2.Hepatic arterial infusion of floxuridine has shown an increase in response rate but little or no improvement in patient survival.

b.Radiation therapy is poorly tolerated by the liver but may be palliative for painful liver metastases.

c.Hepatic artery ligation may cause a dramatic shrinkage in tumor size, but this is only transient. (Although most splanchnic primary cancers metastasize via the portal vein, they quickly become vascularized by the hepatic artery.)

d.Cryoablation, or local freezing of the metastasis, may palliate the symptoms and slow the progression of

disease in unresectable metastases.

e.Surgical resection is the most effective mode of therapy but is limited to the few patients who have unilobar liver lesions and no evidence of extrahepatic disease.

1.The incidence of liver metastasis at the time of surgery for primary colorectal cancer is 8%–25%, and approximately one fourth of these lesions are solitary and resectable, so only about 5% of patients are potential resection candidates.

2.The 5-year survival rate approaches 40% in patients with these criteria. The operative mortality rate is less than 5%, an acceptable risk.

F Hepatic abscesses and cysts

1.Nonviral liver infections (i.e., bacterial, protozoal, or parasitic) generally localize as abscesses or cysts. Mortality without prompt, appropriate treatment is high.

a.Etiology is dependent on environmental factors, particularly geographic location and the presence of endemic parasites.

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b.Clinical presentation. Abscesses and cysts produce few localizing symptoms (i.e., chiefly pain and a mass in the right upper quadrant), while causing major systemic effects (i.e., fever, malnutrition, sepsis, or anemia).

c.Diagnosis. Diagnostic tests used are similar to those used for tumors of the liver (see I B 2).

2.Bacterial abscesses are the most common hepatic abscesses in the Western world.

a.Etiology

1.These are most commonly secondary to infectious processes in the abdomen, particularly cholangitis, appendicitis, or diverticulitis.

2.They may also result from seeding from a distant infectious source, such as endocarditis.

3.In 10%–50% of cases, no source can be identified.

4.The infecting organism is related to the primary source.

a.When the source is abdominal, the most common organisms are gram-negative rods (especially Escherichia coli), anaerobes (typically a Bacteroides species), and anaerobic streptococci (Enterococci).

b.When the source is extra-abdominal, gram-positive organisms predominate.

b.Clinical presentation includes sepsis, fever and chills, leukocytosis, and anemia.

1.Liver function studies show elevated enzyme levels, particularly alkaline phosphatase.

2.The patient may have right upper quadrant pain, and the liver may be tender or enlarged.

3.On occasion, sepsis may be overwhelming.

4.Hemobilia may also occur due to erosion of the abscess into the biliary tree.

c.Treatment

1.The standard surgical treatment for hepatic abscess is operative surgical drainage and antibiotic therapy, which have good results.

2.Hepatic abscesses also are well managed by percutaneous drainage, using catheter aspiration guided by ultrasonic or CT imaging. This closed procedure may be curative, particularly for abscesses with minimal accompanying necrotic debris. Periodic sinograms of the abscess cavity are used to monitor healing and the adequacy of drainage.

3.Multiple abscesses are difficult to manage and rely heavily on appropriate antibiotic coverage.