[Value of albumin RNAscope in situ hybridization in diagnosis and differential diagnosis of hepatocellular carcinoma].

Objective: To investigate the utility of albumin RNAscope in situ hybridization in the diagnosis and differential diagnosis of hepatocellular carcinoma and its mimics. Methods: One hundred and fifty-two cases of hepatocellular carcinoma and its mimics and 33 cases of normal tissue were selected from the pathology database of the Department of Pathology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from January 2013 to December 2019. Tissue microarrays were constructed and RNAscope in situ hybridization was performed to detect the expression of albumin mRNA. Results: No albumin mRNA expression was detected in normal tissues except for the liver. All hepatocellular carcinoma regardless of its degree of differentiation and primary or metastatic nature had detectable albumin mRNA, with strong and diffuse staining in 90.7% (49/54) of cases. While the positive rate of HepPar-1, Arg-1 or one of them by immunohistochemistry was 87.0% (47/54), 85.2% (46/54) and 92.6% (50/54) respectively. The positive rates of albumin mRNA in intrahepatic cholangiocarcinoma and biphenotypic hepatocellular carcinoma were 7/15 and 9/10, respectively. The former showed focal or heterogeneous staining, while the latter showed strong and diffuse staining. The positive rate of hepatoid adenocarcinoma was 8/19, and the albumin expression could be diffuse or focal. Sporadic cases of poorly differentiated gastric adenocarcinoma and metastatic colon adenocarcinoma showed focal staining of albumin mRNA. Conclusions: Detection of albumin mRNA by RNAscope in situ hybridization is of great value for the diagnosis and differential diagnosis of HCC, and the sensitivity may be improved by combining with HepPar-1 and Arg-1. It also offers different diagnostic clues according to different expression patterns.