eMedicine Specialties > Radiology > Gastrointestinal

Hepatic Adenoma

Author: Karen Kodsi Garfield, MD, Attending Physician in Body Imaging, Department of Radiology, St Luke's Hospital
Coauthor(s): Sandor Joffe, MD, Section Chief of Abdominal Imaging, Department of Radiology, Beth Israel Medical Center; Stephen A Okon, MD, Consulting Staff, Assistant Professor of Radiology, Department of Radiology, Beth Israel Medical Center
Contributor Information and Disclosures

Updated: Feb 6, 2009

Introduction

Hepatic adenoma is a rare, benign tumor of the liver.^1,2,3,4 Two types of hepatic adenoma have been identified, including tumors of bile duct origin and tumors of liver cell origin. Hepatic adenomas of bile duct origin are usually smaller than 1 cm and are not of clinical interest; typically, they are found incidentally on postmortem examinations. Hepatic adenomas of liver origin are larger—on average, they measure 8-15 cm—and are often clinically significant.

Pathophysiology

Histologically, sheets of well-differentiated hepatocytes characterize hepatic adenomas. The hepatocytes contain fat and glycogen and can produce bile; however, no bile ducts are present. A characteristic lack of portal vein tracts and terminal hepatic veins is noted. Approximately 80% of adenomas are solitary, and 20% are multiple. Most hepatic adenomas do not contain Kupffer cells.

Frequency

United States

Although hepatic adenomas may be idiopathic, the lesions are most often seen in young women who use oral contraceptives.^1,5,6,7 The incidence among long-term users of oral contraceptives is approximately 4 cases per 100,000.⁷ In women who do not use oral contraceptives or have used them for less than 2 years, the incidence is 1 case per million. In addition, the incidence of hepatic adenomas is increased in patients with glycogen storage disease, diabetes mellitus, hemochromatosis, or acromegaly, as well as in males using anabolic steroids. Case reports by Hill et al indicated that hepatic adenoma is also an unusual complication of pregnancy.⁸ Hepatic steatosis may also be a risk factor.⁹

Mortality/Morbidity

Hepatic adenomas may rupture and bleed, causing right upper quadrant pain^5,10,11 ; rarely, rupture may lead to hemorrhagic shock. Although they are benign lesions, hepatic adenomas can undergo malignant transformation to hepatocellular carcinoma (HCC).^1,6  Malignant transformation is rare, but for this reason, surgical resection is advocated in most patients with presumed hepatic adenomas.^2,3,5,12 However, the primary reason for advocating surgical resection is the risk of hemorrhage. The risk of hemorrhage increases with increasing tumor size (>10.0 cm) and hormone use.¹³

Race

No known racial predilection for hepatic adenomas exists.

Sex

In a retrospective analysis of 437 patients with liver tumors, 44 patients had hepatic adenoma.¹² Of these patients, Weimann et al reported a male-to-female ratio of 1:3.9 (9 men and 35 women).

Age

In the study by Weimann et al, the mean patient age was 34 years (range, 15-64 y) in those affected by hepatic adenoma (44 patients).¹²

Anatomy

Hepatic adenomas typically measure 8-15 cm. Sheets of well-differentiated hepatocytes characterize the lesions. The hepatocytes can produce bile, but no bile ducts are present. Portal vein tracts and terminal hepatic veins are lacking. Almost no hepatic adenomas contain Kupffer cells.

Presentation

Although benign, hepatic adenomas can present a diagnostic challenge because the lesions can be difficult to distinguish from other benign or malignant hepatic tumors. Clinically, patients with hepatic adenoma may be asymptomatic, and lesions may be found incidentally during laparotomy or when radiologic studies are performed. As a result of the large size of the tumor, often 8-15 cm, the patient or physician may notice a right upper quadrant mass or hepatomegaly, resulting in a referral for imaging. Hepatic adenomas can rupture and bleed, causing right upper quadrant pain, which may be mistaken clinically for acute cholecystitis. On rare occasions, rupture may lead to hemorrhagic shock.

Hepatic adenomas  are often seen in young women who use oral contraceptives. The lesions can occasionally regress after cessation of oral contraceptives; however, less commonly, enlargement has been observed after cessation.⁶

Rarely, hepatic adenomas may undergo malignant transformation to hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) levels are helpful in differentiating hepatic adenoma from HCC. A high AFP level indicates the presence of HCC, although not all patients with HCC have elevated AFP levels.⁵ Several cases have been reported in which highly differentiated HCC was diagnosed within an adenoma, although preoperative AFP results were negative.^1,10

In a patient who presents with hepatic hemorrhage that is not preceded by trauma and that is not attributable to anticoagulant therapy, consider the possibility of an underlying liver lesion. The 2 most common liver lesions causing hepatic hemorrhage are hepatic adenoma and HCC. Other neoplasms that can cause hepatic hemorrhage include liver tumors such as focal nodular hyperplasia (FNH), hemangiomas, and metastases. Other rare causes of nontraumatic hepatic hemorrhage exist, such as amyloidosis and HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome, which is seen in a small subset of women with preeclampsia.

In patients with hepatic adenoma, abnormal liver function enzyme levels have been observed, including elevated alkaline phosphatase (ALP) and elevated gamma-glutamyl transpeptidase (GGT) levels. Although patients with FNH often have normal liver function test results, elevated GGT levels may also be seen. Therefore, distinguishing HA from FNH based on laboratory data is usually not possible.

According to Ahmad et al, cytokeratin 7 and cytokeratin 19 immunostains, along with neuronal cell adhesion molecule immunostain, performed on liver needle biopsies can help distinguish hepatic adenoma from focal nodular hyperplasia and may be helpful in diagnosing difficult cases.¹⁴

Iyer et al also confirmed that in hepatic adenoma and focal nodular hyperplasia, specific patterns of immunostains cytokeratin 7, cytokeratin 19, and neuronal cell adhesion molecule are seen, which may suggest the activation of different subsets of hepatic progenitor/stem cell that can be useful diagnostically.¹⁵

Related eMedicine topics:

Hemangiomas, Hepatic

Liver Tumors

Preferred Examination

A combination of multiphasic computed tomography (CT) scans and gadolinium-enhanced magnetic resonance imaging (MRI) is best to identify and characterize most hepatic lesions (see CT Scan and MRI, respectively). Certain characteristics, such as arterial enhancement and the presence of fat and hemorrhage, suggest that the lesion represents hepatic adenoma. If an enhancing central scar is seen, the diagnosis of focal nodular hyperplasia (FNH) can be made. Nuclear medicine studies can also be helpful. Most hepatic adenomas do not demonstrate uptake on sulfur-colloid and gallium-67 (⁶⁷ Ga) scans.¹⁶

Limitations of Techniques

Although CT scanning, MRI, and nuclear medicine studies may help characterize lesions as adenomas, the findings are frequently nonspecific, and biopsy and/or resection may be necessary.

Differential Diagnoses

Focal Nodular Hyperplasia
Hepatocellular Carcinoma
Hepatocellular Carcinoma, Fibrolamellar
Liver, Metastases
Liver, Trauma

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