HEPATOBLASTOMA - DNA NUCLEAR CONTENT, PROLIFERATIVE INDEXES, AND PATHOLOGY

Hepatoblastoma (HB) is the most frequent malignant liver tumor in infa ncy, and both its biological features and its prognostic behavior are still under investigation. DNA content and proliferative activity of t he tumor have been considered as biological parameters related to the tumor's aggressiveness. The present study attempts to investigate the possible association between histologic subtype, DNA content, and prol iferative indices in HE. DNA content and the proportion of cells in th e S-phase were assessed by flow cytometry in 34 cases of HE (14 prior to chemotherapy, 20 after chemotherapy), using formalin-fixed, paraffi n-embedded archival samples. The proliferative cell nuclear antigen (P CNA) labeling index was also evaluated by immunohistochemistry, and bo th the flow cytometry (FC) and the immunohistochemical data were corre lated with tumor pathology. A significant association was found betwee n histological type, DNA content and the percentage of cells in the S- phase, with aneuploidy and the highest proportions of S-phase cells si gnificantly associated with embryonal tumors. The PCNA labeling index was found to be significantly higher in embryonal than in fetal phenot ype. The biological heterogeneity of HE is Confirmed by the different nuclear content of the fetal (diploid) and embryonal (aneuploid) epith elial components of the tumor, also ruling out the likelihood of fetal (diploid) clones deriving from the embryonal (aneuploid) neoplastic c ells. Since the highly proliferative neoplastic clones (i.e., embryona l) are thought to be more sensitive to antimitotic drugs, further stud ies are indicated to determine the relationship between ploidy, prolif erative indices and chemoresponsiveness.