Non-random p53 mutations in pediatric undifferentiated (embryonal) sarcoma of the liver.

Undifferentiated (embryonal) sarcoma of the liver (USL) is a rare hepatic tumor in children. Its pathogenesis is largely unknown, but lines of evidence suggest common links to that of mesenchymal hamartoma of the liver (MH). Previously, we found a p53 mutation in a case of pediatric USL. Recently, there was another published report, demonstrating further evidence of p53 alterations in the adult cases. In this study, we analyzed in three cases of pediatric USL and two cases of MH by using PCR-SSCP and direct sequencing technique. The study identified missense mutations in all three cases of USL, but none of MH. The mutations were found specifically in tumor tissue and not detected in the surrounding normal hepatic tissue. Mutation points were localized in exon 7 (Gly245Ser), exon 6 (Arg196Pro), and exon 8 (Arg273Pro), respectively. Immunohistochemical study of p53 protein expression revealed strong immunoreactivity in cases of USL and negative staining in MH. In summary, this study provided a novel data suggesting that mutations of p53 in pediatric USL are not random genetic events and highly possible to be involved in its tumorigenesis.