PIP: Primary tumors of the liver infrequently develop in patients with a normal liver or in those who have not been exposed to one of several tumor-producing compounds. Hepatocellular adenoma was one of the rarest liver tumors prior to the use of oral contraceptives (OCs). Now the annual incidence in longterm users is estimated at 3-4/100,000. An adenoma that follows OC use is one that often regresses with discontinuation. Focal nodular hyperplasia is a nonencapsulated solitary lesion that has a fibrotic stellate center in which large thick-walled arteries are the source of the blood supply, and occurs most often in women during the menstrual age, and there is no evidence that OCs have increased their frequency. Adenomatous hyperplasia occurs occasionally in patients with submassive necrosis and also in those with cirrhosis. Liver cysts present most often in middle aged women and the ratio of females to males is 4:1. In the US, metastatic carcinoma of the liver is some 18-20 times more frequent and about 85% of these arise in a cirrhotic or precirrhotic liver. Malignant mesenchymal tumors have been associated with exposure to vinyl chloride of injection of Thorotrast. Signs and symptoms of liver disease occur in about 50% of patients with hepatic metastases with hepatomegaly being the most common physical sign. Metastatic carcinoma most often produces multiple umbilicated nodules that involve the liver uniformly. Portal hypertension may be associated with a hepatic neoplasm.