Hepatic adenoma and focal nodular hyperplasia

Abstract

Hepatic adenoma and focal nodular hyperplasia are benign lesions of the liver. The incidence of these conditions has been increasing since 1970. Hepatic adenoma primarily affects young women of childbearing age who have a long history of using oral contraceptives, while focal nodular hyperplasia has a wider age distribution and is not associated with the use of oral contraceptives. The most extensive complication of hepatic adenoma is intratumoral or intraperitoneal hemorrhage, which occurs in 50 to 60 per cent of patients. Patients with focal nodular hyperplasia are usually asymptomatic and rarely experience complications. Hepatic adenoma is distinct from focal nodular hyperplasia both in its clinical behavior and its pathologic features; the two can usually be differentiated radiographically using a combination of radionuclide scanning and angiography. There is a proved association between the use of oral contraceptives and the development of hepatic adenoma; the longer the duration of oral contraceptive use, the more the risk of having hepatic adenoma develop. In addition, users of oral contraceptives who have hepatic adenoma develop are likely to have larger tumors and higher rates of bleeding and rupture than nonusers who have hepatic adenoma develop. Although hepatic adenomas may regress after discontinuation of oral contraceptive use, this is not a consistent finding. In addition, it has now been demonstrated that hepatic adenomas do undergo malignant transformation and that this can be detected by measuring the alpha-fetoprotein level. Focal nodular hyperplasia may be a precursor for fibrolamellar hepatocellular carcinoma. Elective resection of hepatic adenoma has a mortality rate of less than 1 per cent, while the mortality rate with free rupture is 5 to 10 per cent. Because of the relative safety of elective versus emergency resection and the potential for malignant change, the treatment of choice for hepatic adenoma is surgical resection.

PIP: The benign tumors hepatic adenoma and focal nodular hyperplasia are compared in their etiology, differential diagnosis, risk of transformation, and management. Hepatic adenomas range in size from 1-30 cm, averaged 8-10 cm in diameter, contain vacuoles and glycogen, but no Kupfer cells or bile ducts. Adenoma is usually symptomatic, causing pressure or hemorrhage. The risk of developing adenoma is increased with duration of oral contraceptive use, and chance of a larger tumor, a hemorrhage and mortality during pregnancy or surgery is also increased in pill users. Adenoma also occurs in people with Type Ia glycogen storage disease, and is associated with insulin-dependent diabetes. Often stopping oral contraceptives will cause an adenoma to regress. If not, It is best managed by elective resection, with 1% mortality, rather than 5-10% mortality due to spontaneous rupture. Adenomas can progress to adenomatosis, which are inoperable, or malignant transformation. Focal nodular hyperplasia is marked by a stellate scar, sometimes accompanied by hemangioma, but is asymptomatic. It is not increased in oral contraceptive users, but occurs in older women. It can transform to fibrolamellar hepatocellular carcinoma. The 2 benign lesions can be distinguished by radionuclide scanning and angiography. Only fine needle aspiration is advised for biopsy, because of the risk of hemorrhage with adenoma. Focal nodular hyperplasia takes up radionuclide, stains intensely on angiography, and is safe to biopsy percutaneously.