Pathological observations of sinusoid lining endothelial cells and the basement membrane in human hepatocellular carcinoma

OBJECTIVE: To observe changes in sinusoid lining endothelial cells (SEC), type IV collagen (CoIV) and laminin (LM) in chronic liver disease and hepatocellular carcinoma (HCC). To assess the clinicopathological significance of these changes in HCC. METHODS: Thirty specimens were taken from 30 cases of HCC (together with corresponding non‐cancerous tissues), 10 cases of liver cirrhosis, five cases of mild chronic hepatitis and and four cases of normal liver tissues. The specimens were tested for CD34, CoIV and LM by using immunohistochemical methods. CD34, CoIV and LM were semiquantitatively analyzed and assessed in the context of the clinical and pathological features of HCC. RESULTS: CD34 and LM were not present along the sinusoidal walls in normal human liver, however, CoIV was weakly and discontinuously distributed along the sinusoidal walls. In cirrhosis, positive expression of CoIV increased significantly in the sinusoidal walls and became continuous and homogeneous. CD34 and LM were weakly present in the perinodules in a few cases of cirrhosis with obvious inflammatory infiltration. Hepatocellular carcinoma showed a diffuse capillarization, with overexpression of CD34, CoIV and LM. CoIV and LM expression were reduced in poorly differentiated HCC and HCC with portal vein thrombosis. This was frequently accompanied by breaks and losses in the basement membrane. The expression of CD34 in tumors of < 2 cm in diameter was significantly lower than that in tumors of > 5 cm in diameter. The expression of CD34 and LM was markedly increased in HCC compared with non‐cancerous liver tissues. CONCLUSIONS: Diffuse capillarization with overexpression of CD34, CoIV and LM are features of HCC. Frequent breaks in, loss of and decrease of the basement membrane in poorly differentiated tumors and tumors with portal vein infiltration suggests potential metastasis of tumor cells and may play a major role in the metastasis of HCC. CD34 is a useful marker for distinguishing HCC from non‐cancerous liver tissues.