Original ArticlesBranched Chain In Situ Hybridization for Albumin as a Marker of Hepatocellular Differentiation Evaluation of Manual and Automated In Situ Hybridization PlatformsShahid, Mohammad MD*; Mubeen, Aysha MD*; Tse, Julie MD†; Kakar, Sanjay MD‡; Bateman, Adrian C. BSc, MD, FRCPath§; Borger, Darrell Ph.D†; Rivera, Miguel N. MD†; Ting, David T. MD∥; Deshpande, Vikram MD†Author Information 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 Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website, www.ajsp.com. Conflicts of Interest and Source of Funding: Supported by Howard Hughes Medical Institute (M.N.R.), the Burroughs Wellcome Trust (D.T.T., M.N.R.), K12CA087723-11A1 (D.T.T.), and Affymetrix Inc. (D.T.T., M.N.R., V.D.). The authors have disclosed that they have no significant financial interest in, any commercial companies pertaining to this article. Correspondence: Vikram Deshpande, MD, Department of Pathology, Massachusetts General Hospital and Harvard Medical School Boston, Warren 2, 55 Fruit St., Boston, MA 02114 (e-mail: firstname.lastname@example.org). The American Journal of Surgical Pathology: January 2015 - Volume 39 - Issue 1 - p 25-34 doi: 10.1097/PAS.0000000000000343 Buy SDC Metrics 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. © 2015 by Lippincott Williams & Wilkins.