title: Branched chain in situ hybridization for albumin as a marker of hepatocellular differentiation: evaluation of manual and automated in situ hybridization platforms.
abstract: 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 HCCs, and compare its sensitivity with Hep Par 1 and Arginase-1. 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. Fifty-five percent of HCCs were moderately differentiated and 39% poorly differentiated. The sensitivity of ISH for albumin was 99%, with 92 of 93 HCCs staining positive for albumin. In contrast to ISH, the sensitivity of immunohistochemistry for Hep Par 1 and Arginase-1 was 84% and 83%, respectively. The sensitivity of albumin for poorly differentiated HCCs was 99%, whereas that for Arginase-1 and Hep Par 1 was 71% and 64%, respectively. Ninety-seven percent of the HCCs showed albumin positivity in >50% of tumor cells using the ISH platform, as compared with 76% and 70% for Hep Par 1 and Arginase-1 immunohistochemistry, respectively. Three 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. In conclusion, branched chain ISH performed on manual and automated mode is a robust assay for detecting albumin with sensitivity for poorly differentiated HCCs superior to Arginase-1 and Hep Par 1. When interpreted in conjunction with Arginase-1, albumin ISH offers a high level of sensitivity and specificity.
authors.affiliation: Departments of *Surgery †Pathology ∥Medicine, Division of Oncology, Massachusetts General Hospital and Harvard Medical School Boston, MA ‡UCSF and VA Medical Center, San Francisco, CA §Department of Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shahid
authors.forename: Aysha
authors.initials: A
authors.lastname: Mubeen
authors.forename: Julie
authors.initials: J
authors.lastname: Tse
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kakar
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Bateman
authors.forename: Darrell
authors.initials: D
authors.lastname: Borger
authors.forename: Miguel N
authors.initials: MN
authors.lastname: Rivera
authors.forename: David T
authors.initials: DT
authors.lastname: Ting
authors.forename: Vikram
authors.initials: V
authors.lastname: Deshpande
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001119:Arginase / Q000032:analysis; D057205:Automation, Laboratory; D014408:Biomarkers, Tumor / Q000235:genetics*; D001706:Biopsy; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000032:analysis; D006528:Carcinoma, Hepatocellular / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D002454:Cell Differentiation; D003937:Diagnosis, Differential; D004739:England; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization / Q000379:methods*; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012333:RNA, Messenger / Q000235:genetics*; D012709:Serum Albumin / Q000235:genetics*; D000075462:Serum Albumin, Human; D046888:Tissue Array Analysis; D014481:United States
chemical_list: C422455:ALB protein, human; D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D012709:Serum Albumin; C574619:ARG1 protein, human; D001119:Arginase; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D000075462:Serum Albumin, Human