Pathology of liver tumours
The liver is an important site for both primary and metastatic tumours. Hepatocellular carcinoma is a major cause of cancer death worldwide, and in patients with cirrhosis is the most likely cause of hepatic malignancy. In non-cirrhotic patients, the commonest hepatic presentation of malignant disease is metastasis from other sites, most commonly colon, lung, stomach, pancreas and breast. In hepatocellular carcinoma, the malignant cells show differentiation resembling hepatocytes. There is a strong link with chronic viral hepatitis and cirrhosis of any cause, although an unusual slow-growing variant of hepatocellular carcinoma called fibrolamellar carcinoma does not show these associations. Cholangiocarcinoma is adenocarcinoma arising in a bile duct, and is usually of unknown cause although some cases are linked with chronic biliary inflammation or infection. Intrahepatic cholangiocarcinoma is increasingly often diagnosed, although definitive diagnosis requires clinical exclusion of a metastasis from elsewhere. There is a variety of benign liver tumours, often manifesting incidentally during investigations. Some have a risk of malignant progression (dysplastic nodules in cirrhotic liver, some hepatocellular adenomas), while others are notable mainly for mimicking more serious disease than for great intrinsic significance.