[Histopathological differential diagnosis of primary liver tumors]

The most common primary hepatic malignancy is hepatocellular carcinoma, which constitutes 80-85% of all malignant epithelial neoplasms originating in the liver. The second most common primary hepatic malignancy is cholangiocellular carcinoma. In recent years, remarkable progress has been made in elucidating the molecular pathology of hepatic tumors. Advances in our understanding of molecular subtypes have led to a creation of a new classification system of hepatocellular adenomas, with important genotype-phenotype correlations and easy application to routine diagnostic practice. In the field of early hepatic neoplasia, a consensus on the definition of dysplastic nodules and early hepatocellular carcinoma has been reached. Immunohistochemical detection of glypican-3 and stromal invasion are used for the differential diagnosis. A lot of problems still exist in the category of mixed hepatocellular and cholangiocellular carcinoma. Although this category is recognized in the WHO classification, confusing terminology has been generated to describe tumors with morphological features of both HCC and CC. We further specify problems and pitfalls of the differential histopathological diagnosis of liver malignant tumors.