ABSTRACT
ObjectiveTo investigate whether small epithelial cells (SEC) exist in human hepa- tocellularcarcinoma (HCC) and if so, whether they exhibit immunolabelling for both albumin and cytokeratin 7 (CK7). MethodsThirty cases of human HCC from operative specimens were investi- gated by immunohistochemistry with antibody against albumin, a marker of hepatocyte differentiation and CK7, a marker of biliary differentiation. Ten cases were investigated by electron microscopy and by immuno- electron microscopy. ResultsThe SEC were found in 20 of 30 cases that located around the edges of the tumors and appeared as proliferative small biliary ductules. Under electron microscopy they were of small size, contained sparse cytoplasm, few free ribosomes, intracellular tonofilarnents, and intercellular junctions. Immunoelectron microscopically the SEC exhibited labelling for both albumin and CK7 in 5 out of 10 cases. ConclusionSEC in human HCC are found that represent the same mor- phology like those seen in hepatoblastoma and biliary atresia, co- expressed markers for hepatocytic and biliary differentiation.