What is HEPATIC ADENOMA?

Hepatocellular adenoma or Hepadenoma is an uncommon benign liver tumour which is associated with the use of oral contraceptive pills with a high oestrogen content. MRI is the most useful investigation in the diagnosis and workup. All hepatocellular adenoma should be surgically resected, because of the risk of rupture causing bleeding and because they may contain malignant foci.

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


Pathophysiology: Histologically, sheets of well-differentiated hepatocytes characterize HAs. 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 HAs do not contain Kupffer cells.

HAs often are seen in young women on oral contraceptives. The lesions occasionally can regress after cessation of oral contraceptives; however, less commonly, enlargement also has been observed after cessation.

Rarely, HAs may undergo malignant transformation to HCC. Alpha-fetoprotein (AFP) levels are helpful in differentiating HA from HCC. A high AFP level indicates the presence of HCC, although not all patients with HCC have elevated AFP levels. Several cases have been reported in which highly differentiated HCC was diagnosed within an adenoma, although preoperative AFP results were negative (Casillas et al, 2000).

Mortality/Morbidity: HAs may rupture and bleed, causing right upper quadrant pain. Rarely, rupture may lead to hemorrhagic shock. Although they are benign lesions, HAs can undergo malignant transformation to hepatocellular carcinoma (HCC). Although malignant transformation is rare, for this reason, surgical resection is advocated in most patients with presumed HAs.

Frequency:


In the US: Although HAs may be idiopathic, the lesions most often are seen in young women using oral contraceptives. The incidence among long-term users of oral contraceptives is approximately 4 cases per 100,000. 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, incidence of HAs is increased in patients with glycogen storage disease, diabetes mellitus, hemochromatosis, acromegaly, and in males using anabolic steroids. Case reports by DeMenis et al in 1997 indicate that HA is a complication of pregnancy.
Mortality/Morbidity: HAs may rupture and bleed, causing right upper quadrant pain. Rarely, rupture may lead to hemorrhagic shock. Although they are benign lesions, HAs can undergo malignant transformation to hepatocellular carcinoma (HCC). Although malignant transformation is rare, for this reason, surgical resection is advocated in most patients with presumed HAs.

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