Background: Intratumoral DNA heterogeneity provides important information regarding biologic and clinical behavior. The purpose of this study was to evaluate the incidence of DNA heterogeneity in small hepatocellular carcinoma (HCC) nodules.
Methods: The DNA content of 28 surgically resected small HCC nodules (< or = 3.0 cm) was measured using flow cytometry of fresh or frozen samples taken from different parts of each nodule with reference to the macroscopic features.
Results: Of the 28 small HCC nodules, 14 (50.0%) had only DNA diploid stemline characteristics. Five nodules (17.9%) manifested DNA diploid and DNA aneuploidy within the same tumor. Of the remaining nine nodules (32.1%) that showed only DNA aneuploidy, two contained tumor tissues with apparently different DNA content. Thus, DNA heterogeneity was found in 7 (25.0%) of 28 nodules. DNA heterogeneity correlated well with macroscopic histologic features. All four early HCC were composed of only DNA diploid cells, whereas three of six nodule-in-nodule lesions were composed of DNA heterogeneous cells, in which the inner obviously cancerous nodule showed DNA aneuploidy and the outer well differentiated HCC portion demonstrated DNA diploid. Four of 18 overt HCC nodules showed DNA heterogeneity; 2 of these 4 nodules showed both diploid and aneuploid peaks, and the other 2 two showed different aneuploid peaks within the same nodule.
Conclusions: DNA heterogeneity correlating with macroscopic features is found frequently even in small HCC nodules. Therefore, multiple sampling based on macroscopic features is required for the accurate assessment of DNA ploidy, particularly when the information about DNA ploidy is used as a prognostic indicator.