The field of liver tumors and tumor-like lesions in adults and children has experienced tremendous advances in recent years. Specifically, the recognition of novel entities, deepened insights into known tumors, and refinement of classifications have necessitated continual updates and reappraisals. In addition, previous understanding of hepatic carcinogenesis and tumor progression has been transformed by the very rapid evolution of our understanding of cell biology, genomics, signaling pathways, cell interactions, and mechanisms of invasion and spread of hepatic tumor cells. These general pathology issues must be combined with surgical pathology if a comprehensive understanding of liver tumor pathology is to be achieved.