Molecular characteristics of fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FLC) occurs in non-cirrhotic liver and the etiopathogenesis is still obscure. Both hepatocellular and cholangiocellular markers are expressed in the tumor, however, molecular alterations and altered pathways playing role in the tumor pathogenesis are not clearly identified. The purpose of the present study was to compare the expression level of EGFR, syndecan-1 and ß-catenin in FLC, conventional hepatocellular carcinoma (cHCC) and cholangiocellular carcinoma (CCC) and to investigate the possibility of mutation both in EGFR and K-RAS. Eight FLCs were compared with 7 cHCCs, 7 CCCs and 5 normal liver samples. Cytokeratins 7, 8, 18, 19, HepPar1 (HSA), EGFR, syndecan-1 (CD138) and ß-catenin were detected by immunohistochemistry. In addition EGFR, ß-catenin and syndecan-1 were evaluated by digital morphometry and K-RAS, EGFR mutations in FLC cases using paraffin-embedded samples. All FLCs were positive for HepPar1 (HSA) and cytokeratins 7, 8, 18, but negative for cytokeratin 19 by immunohistochemistry. EGFR was significantly overexpressed in all three tumor types, being highest in FLCs (p = 0,0001). EGFR, K-RAS mutation analyses revealed no mutations in exons studied in FLCs. Our findings proved that expression of EGFR is higher in FLC than in other types of primary malignant hepatic tumors and no K-RAS mutation can be detected, so FLC is a good candidate for anti-EGFR treatment.