Branched Chain In Situ Hybridization for Albumin as a Marker of Hepatocellular Differentiation

Abstract

Introduction Albumin, widely recognized as a highly sensitive and specific marker of hepatocellular carcinoma (HCC) is currently unavailable in the diagnostic laboratory because of the lack of a robust platform. In a prior study we detected albumin mRNA in the majority of intrahepatic cholangiocarcinomas using a novel branched chain RNA in situ hybridization (ISH) platform. We now explore the utility of albumin ISH as a marker of hepatocellular differentiation in hepatocellular carcinomas, and compare its sensitivity with Hep Par 1 and Arginase-1. Methods We evaluated 93 HCCs and its mimics including neuroendocrine tumors of the gastrointestinal tract (n= 31), neuroendocrine tumors of the pancreas (n= 163), melanoma (n= 15), and gallbladder carcinoma (n=34). We performed ISH for albumin and immunohistochemistry for Hep Par 1 and Arginase-1. Five previously uncharacterized hepatic neoplasms from our files were also evaluated. Immunohistochemistry for Arginase-1 was performed on 59 intrahepatic cholangiocarcinomas. In addition, 43 HCCs evaluated on the manual platform, were also examined on the automated instrument. Results 55% of HCCs were moderately differentiated and 39% poorly differentiated. The sensitivity of ISH for Albumin was 99% with 92 of 93 of HCCs staining positive for albumin. In contrast to ISH, the sensitivity of immunohistochemistry for Hep Par1 and Arginase-1 was 84 % and 83 %, respectively. The sensitivity of albumin for poorly differentiated HCCs was 99%, while that for Arginase-1 and Hep Par 1 was 71% and 64%, respectively. 97% of the HCCs showed albumin positivity in >50% of tumor cells using the ISH platform, as compared to 76% and 70% for Hep Par 1 and Arginase-1 immunohistochemistry, respectively. 3 of the 5 previously uncharacterized neoplasms were positive for albumin ISH. Automated albumin ISH platform performed equivalently to the manual format, with albumin reactivity in >50% of tumor cells in all 43 cases that were tested on both platforms. All non- HCCs were negative for albumin. All 59 intrahepatic cholangiocarcinomas were negative for Arginase-1. Conclusion Branched chain ISH performed on manual and automated mode is a robust assay for detecting albumin with sensitivity for poorly differentiated HCC superior to Arginase-1 and Hep Par 1. When interpreted in conjunction with Arginase-1, albumin ISH offers a high level of sensitivity as well as specificity.

Reg proteins promote acinar-to-ductal metaplasia and act as novel diagnostic and prognostic markers in pancreatic ductal adenocarcinoma

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Albumin expression distinguishes bile duct adenomas from metastatic adenocarcinoma

“…Albumin is a protein synthesized by hepatocytes, and has recently been shown to be a highly sensitive and specific marker for hepatocellular differentiation when detected by branched‐chain in‐situ hybridization (bISH) . In a recent study, we showed that >95% of intrahepatic cholangiocarcinomas stain positively for albumin, suggesting that intrahepatic cholangiocarcinomas and hepatocellular carcinomas arise from a common progenitor cell.…”

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