Vascularization of small hepatocellular carcinomas: correlation with differentiation

Background: Hepatocellular carcinoma (HCC) is generally considered a hyperv ascular tumor when visualized by angiography. However, small HCCs are not a lways found to be hypervascular. Methods: To evaluate this, 50 HCCs less th an or equal to 3 cm in diameter were studied. The 50 tumors consisted of 16 well-differentiated HCCs, 25 moderately differentiated HCCs, and 9 that we re each a mixture of well- and moderately differentiated HCC. Results: The mean number of portal tracts in the well-differentiated HCCs was 34% of the number in the surrounding nontumorous liver, and few intratumoral arteriol es were seen. In contrast, the mean number of portal tracts in the moderate ly differentiated HCCs was 0.6% of the number in the surrounding nontumorou s liver, and abundant intratumoral arterioles were seen. For HCCs that cont ained both well-differentiated and moderately differentiated tumor, the dis tribution of portal tracts and intratumoral arterioles in each portion was similar to that seen in well-differentiated or moderately differentiated HC C alone, respectively. HCCs that were larger than 1.5 cm in diameter had fe wer portal tracts and more intratumoral arterioles than HCCs whose diameter s were less than or equal to 1.5 cm. Conclusions: As small HCCs increase in size and become increasingly dedifferentiated, the number of portal tracts apparently decreases and intratumoral arterioles develop. These findings m ay reflect changes in the hemodynamics as the HCC develops.