A cytokeratin-immunohistochemical study of hepatoblastoma.

Six cases of hepatoblastoma (five epithelial, one mixed epithelial-mesenchymal) were studied on serially cut cryostat sections, using a panel of monoclonal antibodies directed against individual cytokeratins, vimentin, and desmin, in an indirect immunoperoxidase procedure. Embryonic and fetal-type tumor cells expressed the "hepatocellular" cytokeratins no. 8 and 18 but, surprisingly, also expressed the "bile duct type" cytokeratin no. 19. In addition, two cases had a number of tumor cells which were also positive for the "bile duct type" cytokeratin no. 7. Cells embedded in osteoid-like material were immunoreactive for vimentin but also for cytokeratins no. 7, 18, and 19. Gel electrophoresis, and Western blotting of cytoskeletal extracts, confirmed the immunohistochemical data. The implications of these findings for the histogenesis of hepatoblastoma are discussed in this report.