Hepatocellular carcinoma: It accounts for more than 90% of primary liver cancer and is the most common type of pathology. 1.Basic typing: it can be divided into nodular, massive and diffuse types; also refer to the classification of “five large and six subtypes” developed by Chinese Hepatocellular Carcinoma Pathology Research Collaborative Group in 1977. The tumor diameter <25px is called microscopic cancer, 1-3cm is called small liver cancer, 3-125px is called medium liver cancer, 5-250px is called large liver cancer, >250px is called massive liver cancer, and small foci scattered throughout the liver (similar to cirrhotic nodules) are called diffuse liver cancer. At present, the standard of small liver cancer in China is: the maximum diameter of a single cancer nodule is ≤75px; the number of multiple cancer nodules does not exceed 2, and the total maximum diameter of these nodules is ≤75px. small liver cancer is small in size, mainly single nodular and swelling growth, with clear demarcation or envelope formation with surrounding liver tissues, and has the characteristics of slower growth, lower malignancy, less possibility of metastasis and better prognosis. 2.Histological characteristics: The cancer cells are mainly arranged in the form of beams and cords, with polygonal shape, eosinophilic cytoplasm, round nuclei, and blood sinusoids lining between the beams and cords; there may be many special types of cytology and histology, and if pseudoglandular duct structure appears, it may resemble intrahepatic bile duct cancer and metastatic adenocarcinoma, which needs to be distinguished. Representative immunohistochemical markers: hepatocyte antigen shows positive cytoplasm, polyclonal carcinoembryonic antigen shows positive cell membrane capillary bile ducts, CD34 shows diffuse distribution of hepatic sinusoidal microvessels, and phosphatidylinositol protein-3 is usually expressed in the cytoplasm of HCC cancer cells. Histopathological examination of liver biopsy for small lesions should be performed and evaluated by experienced pathologists; GPC-3, heat shock protein 70 and glutamine synthetase staining can be performed, and if two of the three items are positive, HCC can be diagnosed. Intrahepatic cholangiocarcinoma: It is less common and originates from the epithelial cells of bile duct secondary branches far from the intrahepatic bile ducts, and generally accounts for only Q5% of primary hepatocellular carcinoma. 1. Gross typing: It can be divided into nodular, periductal infiltrative, nodular infiltrative and intraductal growth type. 2. Histological features: adenocarcinoma is the main structure, and the cancer cells are arranged into a glandular cavity similar to bile ducts, but the glandular cavity does not contain bile but secretes mucus. The cancer cells are rectangular or low columnar in shape, with lightly stained cytoplasm, transparent cytoplasm and abundant fibrous interstitium, i.e. the cancer cells are surrounded by more fibrous tissue. There are also several cytologic and histologic specific types, and if there is beam-like arrangement, it may resemble hepatocellular carcinoma, which needs to be distinguished. The degree of differentiation of cancer cells can be classified as good, moderate or poor. 3. Representative markers: immunohistochemical examination of cytokeratin 19 and fucose-1 can show positive cytoplasm. 3. Mixed type hepatocellular carcinoma: that is, HCC-ICC mixed type hepatocellular carcinoma, which is relatively rare. Within a liver tumor nodule, both HCC and ICC components are present, and the two are mixed in distribution with unclear boundaries, expressing their respective immunohistochemical markers. IV. Other types. There are some rare types of primary hepatocellular carcinoma, such as clear cell type, giant cell type, sclerosing type and hepatic fibrous lamellar carcinoma. Among them, FLC is a special and rare histological subtype of HCC; it is characterized by being seen mostly in young patients under 35 years of age, usually without hepatitis B virus infection and hepatic sclerosis background, less malignant than HCC, and the tumor is often more limited, so this disease usually has the chance of surgical resection and better prognosis. Most of the tumors are located in the left lobe of the liver, often single, with clear boundaries, scalloped edges and hard textures.