Numerous advances in our understanding of the pathology and molecular features of liver tumors have been made since the publication of the previous series, nearly two decades ago. Examples of recent advances include the identification of novel entities, including their precursor lesions, the discovery of key molecular changes, including the fusion transcript between the DNAJB1 gene and the PRKACA gene in fibrolamellar carcinoma, the use of glutamine synthetase in the diagnosis of focal nodular hyperplasia, and the subtyping of hepatocellular adenomas using molecular and immunohistochemical methods. Together with the more unified classification and terminology of intrahepatic bile duct tumors and their precursors, these advances call for updated information that is presented in this volume.