Histological types of liver cancer

Liver cancer can be divided into hepatocellular carcinoma, cholangiocarcinoma and mixed liver cancer according to histological type.

(1) Hepatocellular carcinoma: the most common, generally accounting for about 90% of primary liver cancer. Cancer cells retain some of the characteristics of hepatocytes and do not form liver lobules. Cancer cells are polygonal, with rich cytoplasm, large nuclei and obvious nucleoli. Bile granules can be seen in the cytoplasm of well-differentiated ones. Cancer cells are often arranged in nests or cords, with abundant blood sinusoids between cancer nests. Morphological variations and degenerative changes such as fatty degeneration may occur. In 1956, Edmondson-Steinei divided the degree of differentiation of hepatocellular carcinoma into four levels: grade I is highly differentiated and rare; grades II and III are moderately differentiated and the most common; and grade IV is poorly differentiated and rare. Well-differentiated liver cancer is very similar to normal liver cells or liver cells in hyperplastic nodules, with gradually increasing atypia, often manifested as reduced cytoplasm and increased water content. Hepatocellular carcinoma is mostly grayish white or yellow, and is soft in texture due to its rich blood supply, making it prone to rupture.

(2) Cholangiocarcinoma: It is less common, generally accounting for about 5% of primary liver cancer. Cholangiocarcinoma can occur in any lobe of the liver. Pathologically, it can be divided into multinodular, infiltrative, and diffuse types. The cut surface is grayish white, and a umbilicus can be seen on the surface of the liver. The proportion of patients with cirrhosis is lower than that of hepatocellular carcinoma. The cancer cells are cubic or columnar, and the cytoplasm is transparent. The cancer cells are arranged in a glandular cavity similar to the bile duct, but the glandular cavity does not secrete bile but secretes mucus. The cancer cells do not contain bile pigments, little or no glycogen, and there is a lot of fibrous tissue around the cancer cells, which is different from hepatocellular carcinoma. Because cholangiocarcinoma has extensive fibrosis, it is grayish white in color and tough in texture. The surface may be concave due to fiber contraction, and generally does not bleed or rupture.

(3) Mixed liver cancer: rare. It is a mixed type of hepatocellular carcinoma and cholangiocarcinoma, with the two mixed and unclear boundaries.

(4) Fibrolamellar liver cancer: Fibrolamellar liver cancer is a special histological subtype of hepatocellular carcinoma that has been newly recognized in recent years. It has many characteristics different from ordinary hepatocellular carcinoma, such as being more common in young people, often single tumors, slow growth, rarely accompanied by liver cirrhosis, and rarely HBV infection. AFP is mostly negative, the surgical resection rate is high, and the prognosis is good. The median survival of ordinary liver cancer is 6 months, while that of fibrolamellar liver cancer can reach 32-68 months; the median survival after resection is 22 months for the former and 50 months for the latter. Therefore, it is advisable to be cautious when evaluating the efficacy of different treatment methods. The pathological histological diagnostic criteria of fibrolamellar liver cancer are: ① strong eosinophilic granules are present in the cancer cell plasma; ② a large number of parallel lamellar fibrous matrix are present between cancer cell nests. In Western countries, the proportion of fibrolamellar liver cancer in hepatocellular carcinoma is relatively high, while it is rare in my country, Japan, and southern Africa, where liver cancer is highly prevalent.