Efficacy of expressions of Arg-1, Hep Par-1, and CK19 in the diagnosis of the primary hepatocellular carcinoma subtypes and exclusion of the metastases

Abstract

Many conflicts arise using immunohistochemistry of Hepatocellular carcinoma (HCC), some of these conflicts arise from the biliary part within the tumor itself or from liver metastasis. The aim of this study is to investigate the extent of Arg-1, HepPar-1, and CK-19 expressions in the primary HCC subtypes as well as studying of some metastatic cases to find a distinctive immunohistochemical panel utilizing it to differentiate between these entities. Material and methods. A paraffin-embedded block including 62 cases of primary HCC, and 18 cases diagnosed as metastatic tumors, were subjected for this study using Anti-liver Arginase antibody (ab125134 Cambridge, USA, polyclonal antibody, 3.75 µg/ml), HepPar-1 (polyclonal mouse antibody OCH1E5; 1:600; DAKO, CA, USA), and CK 19 Anti-Cytokeratin 19 antibody (ab15463, rabbit polyclonal antibody; 1:100; Cambridge, USA). The intensity of immunostaining was scored (0 to 3+). Nuclear and cytoplasmic staining with Arg-1 and cytoplasmic for both HepPar-1 and CK 19 are reported. Results. The histopathological patterns were mainly trabecular no=(24, 38.7%), and pseudoglandular (no=14, 22.5%), mixed hepatocellular cholangio-carcinoma was observed in one case (1.6%). Arginase-1 positivity was in 55 cases (88.7%) opposite to 46 (74.19%) and 8 (12.9%) for HepPAr.1% -1 and CK 19, respectively. The intensity of expression was marked in well and moderate differentiation for Arg-1 and HepPar-1and in poorly differentiated for CK 19. Metastatic carcinoma cases revealed two cases positive for Arg-1 (11.1%), 4 cases (22.2%) positive for HepPar-1, and 13 cases (72.2%) positive for CK 19. Conclusion. Arg-1 and HepPar-1 are confirmative in the diagnosis of primary HCC in most cases, either separately or collectively but the priority of selection leans more towards Arg-1. Arg-1 and HepPar-1 positive with negative CK 19 expressions give more support to diagnosis of primary HCC while the reverse will support the diagnosis of tumour of biliary origin or liver metastasis.