Hepatocellular adenoma is the most important benign tumor to recognize. It occurs primarily in women of childbearing age, particularly those taking oral contraceptives, possibly via estrogen’s effects (1).

Most adenomas are asymptomatic, but large ones may cause right upper quadrant discomfort. Rarely, adenomas manifest as peritonitis and shock due to rupture and intraperitoneal hemorrhage. Rarely, they become malignant.

Diagnosis is often suspected based on ultrasound or CT results, but biopsy is sometimes needed for confirmation.

Adenomas due to contraceptive use may regress if the contraceptive is stopped. If the adenoma does not regress or if it is subcapsular or > 5 cm, surgical resection is often recommended.

This localized hamartoma may resemble macronodular cirrhosis histologically. Diagnosis is usually based on MRI or CT with contrast, but biopsy may be necessary for confirmation. Treatment is rarely needed.

Hemangiomas are usually small and asymptomatic; they occur in 1 to 5% of adults. Symptoms are more likely if they are > 4 cm; symptoms include discomfort, fullness, and, less often, anorexia, nausea, early satiety, and pain secondary to bleeding or thrombosis. These tumors often have a characteristic highly vascular appearance. Hemangiomas are found incidentally during ultrasonography, CT, or MRI. CT typically shows a well-demarcated, hypodense mass; when contrast is used, there is early peripheral enhancement, followed by later centrifugal enhancement. Treatment is usually not indicated. Resection can be considered if symptoms are troublesome or if a hemangioma is rapidly enlarging.

In infants, hemangiomas often regress spontaneously by age 2 yr. However, large hemangiomas occasionally cause arteriovenous shunting sufficient to cause heart failure and sometimes consumption coagulopathy. In these cases, treatment may include high-dose corticosteroids, sometimes diuretics and digoxin to improve heart function, interferon alfa (given sc), surgical removal, selective hepatic artery embolization, and, rarely, liver transplantation.

Lipomas (usually asymptomatic) and localized fibrous tumors (eg, fibromas) rarely occur in the liver.

Benign bile duct adenomas are rare, inconsequential, and usually detected incidentally. They are sometimes mistaken for metastatic cancer.