Histopathological evidence for the existence of primary liver progenitor cell cancer: insight from cancer stem cell pathobiology.

Background: Primary liver progenitor cell cancer is a rare disease entity. Current nomenclature of primary liver cancer with prominent progenitor features is not comprehensive. This study was aimed to investigate the existence of this type of primary liver cancer and characterize it immunohistopathologically based on the emerging understanding of cancer stem cell pathobiology. Methods: Surgical specimens from a primary liver cancer were stained with antibodies against well-defined markers of progenitor cells, stemness, and differentiation toward hepatocytes or cholangiocytes. Comparative interpretation of images was processed considering the histological morphology and characteristic markers. Results: The primary liver cancer consisted of CD24(+) cancer progenitor cells and CD90(+) mesenchymal stromal cells, which were intimately mixed. CD24(+) cancer cells demonstrated bidirectional trends of differentiation: bile ductule transformation and trabecular or nested cell clusters toward hepatic lineage. Moderate number of CD4(+) and CD8(+) T cells infiltrated the CD90(+) cancer-associated stroma. Conclusions: We provided the corroboration that liver progenitor cells can form primary liver cancer, not just presented as a few side populations of cancer stem cells. Its existence might have significance for future stem cell therapeutic intervention targeting liver diseases.