To investigate the characteristics of hepatocellular carcinoma (HCC) at contrast-enhanced ultrasonography (CEUS) with different tumor size and the degree of HCC histologic differentiation.

Of 57 consecutive patients with core needle biopsy or surgical specimen histologically proved HCC, the relationship between tumor size and histologic differentiation was analyzed by using R×C χ² test. The enhancement degrees and enhancement patterns of each group were compared, and the influence of cirrhosis on contrast-enhanced patterns was investigated by Fisher exact test.

There were 20 small HCC, 15 moderated-size HCC, 22 large HCC and 10 well differentiated HCC, 27 moderately differentiated HCC, 20 poorly differentiated HCC. And there were 36 patients with hepatitis B viral hepatitis related nodular cirrhosis, and 21 patients without nodular cirrhosis of the liver. (1) The enhancement degrees of small HCC were homogeneous hypervascularity, the moderated-size HCC were homogeneous hypervascularity or heterogeneous hypervascularity, and the large HCC were heterogeneous hypervascularity. The pattern of contrast-enhanced US has no significant difference among three groups.The small HCC showed a significantly different enhancement compared with moderated-size HCC and large HCC (χ²=7.445, P<0.05; χ²=0.481, P<0.01). (2) The well differentiated HCC, moderately differentiated HCC and poorly differentiated HCC could show homogeneous hypervascularity or heterogeneous hypervascularity, there were no significant differences on enhancement degree among three groups. The well differentiated HCC showed fast wash-in and fast wash-out, iso-wash-in and iso-wash-out or fast wash-in and late wash-out patterns. Moderated and poor differentiated HCC showed fast wash-in and fast wash-out. There were significant differences between well differentiated HCC with moderated HCC and poor HCC (χ²=10.702, 8.505, both P<0.01). But no significant dirrerence was found between moderated and poor HCC. (3) The enhancement pattern between patients with and without cirrhosis were compared, and negative result were obtained.

The enhancement degree was dependent with tumor size, the large tumor tend to present heterogeneous hypervascularity. It may be related to the microvescular density distribution and necrosis formation. The enhancement pattern was dependent with histologic differentiation. Extended observation in the portal phase is important to detect the occurence of late washout in well differentiated HCC, which is useful to improve the diagnostic accuracy of CEUS in HCC.