Combined hepatocellular/cholangiocellular carcinoma with sarcomatoid features: genetic analysis for histogenesis

The histogenesis of sarcomatoid transformation in hepatocellular carcinomas (HCCs) and cholangiocellular carcinomas (CCCs) remains unclear. In the cur rent case, microsatellite loss of heterozygosity (LOH) assay and mutational analysis of the p53 gene with immunohistochemical examination were perform ed to investigate the histogenesis of each component. The tumor was compose d of two parts: one part comprised poorly differentiated HCC (HCC portion), while the other part included undifferentiated, sarcomatoid HCC and CCC (c ombined portion). LOH at D8S555 was detected in both portions. 1-bp cytosin e was deleted at codon 241 of exon 7 of the p53 gene in the combined portio n. Immunohistochemically, p53 accumulated in the nuclei of undifferentiated , sarcomatoid HCC and CCC cells, suggesting that the p53 gene mutation migh t be common in these components. These results support the hypothesis that undifferentiated, sarcomatoid HCC and CCC could be offspring from the origi nal HCC. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.