Comprehensive genetic analysis of cholangiolocellular carcinoma with a coexistent hepatocellular carcinoma-like area and metachronous hepatocellular carcinoma

Aim: The genetic profile of cholangiolocellular carcinoma (CLC) and its origin in relation to hepatocellular carcinoma (HCC) remain unclear. To elucidate the genetic profile of CLC, a comprehensive analysis of genetic mutations was carried out in a case of CLC with an HCC-like focal area and metachronous HCC. Method: Liver tissue was obtained from CLC, a co-existent HCC-like area, and metachronously developed HCC by laser capture microdissection of formalin-fixed paraffin-embedded specimens obtained by hepatectomy. Gene mutational profiles were analyzed comprehensively by next-generation sequencing and digital PCR. Relationships among gene profiles, immunohistochemistry, and clinicopathological findings were investigated. Results: Mutations in EGFR, PTEN, RB1, TP53, and ERBB2 were found in CLC, whereas mutations in KIT, BRAF, PTEN, TP53, and SMAD4 were found in the coexistent HCC-like area. Only the mutation in PTEN has a common Catalogue of Somatic Mutations in Cancer ID in the CLC and coexistent HCC-like area, and is related to the kinase-RAS module. In contrast, no cancer-related mutations were found in the metachronous HCC. No TERT mutations were found in any of the regions by digital PCR. Immunohistochemical staining for p53 was negative in CLC, although ≤10% positive in the coexistent HCC-like area. Immunostaining of C-kit, HER2, PTEN, and SMAD4 were negative. Conclusion: The genomic features of CLC and the focal area of an HCC-like region differ, but are related to the kinase-RAS module. The development of carcinogenesis in the CLC and HCC-like areas in this case might differ, following a common PTEN mutation, although alteration of the kinase-RAS module is the most common molecular event in CLC.