Research ArticlesA Comprehensive Evaluation of Special AT-rich Sequence-binding Protein 2 (SATB2) Immunohistochemical Staining in Mucinous Tumors From Gastrointestinal and Nongastrointestinal SitesRamos, Benjamin D. MD; Brettfeld, Stefan MD; Berry, Ryan S. MD; Routh, Joshua K. MD; Martin, David R. MD; Hanson, Joshua A. MDAuthor Information Department of Pathology, University of New Mexico School of Medicine, Albuquerque, NM The authors declare no conflict of interest. Reprints: Joshua A. Hanson, MD, Department of Pathology, University of New Mexico School of Medicine, MSC08 4640, Albuquerque, NM 87131 (e-mail: [email protected]). Applied Immunohistochemistry & Molecular Morphology: May/June 2019 - Volume 27 - Issue 5 - p 378-385 doi: 10.1097/PAI.0000000000000627 Buy Metrics Abstract Special AT-rich sequence-binding protein 2 (SATB2) is an accurate marker for conventional colorectal carcinoma (CRC), although its sensitivity and specificity in mucinous tumors from the colon and other sites remains unknown. The objective of this study is to evaluate the accuracy of SATB2 expression detected by immunohistochemical assay, as a marker of primary CRC in mucinous adenocarcinomas. SATB2 immunohistochemical stains were performed on whole sections from 63 conventional CRCs (controls), 47 mucinous CRCs (mCRC), and 182 noncolorectal mucinous tumors. SATB2 intensity was scored as 1 to 3 based on the estrogen receptor/progesterone receptor grading system, and the percent positive cells was scored in broad categories as follows: 0 (negative)≤5%, 1=5% to 49%, 2≥50%. An optimal sensitivity/specificity pairing (83% and 95%, respectively) was achieved in the mCRCs when the additive intensity and percent score was ≥3 (ie, intensity score+percent score=total score). Defining this total score (histologic score/“H score”) as a “positive” result, the sensitivity of SATB2 for conventional CRC was 98% (62/63) versus 83% (39/47) for mCRCs (P=0.02); whereas 5% (9/182) of all noncolorectal mucinous tumors were considered positive. SATB2 especially demonstrated reduced specificity when applied to mucinous gastroesophageal and breast carcinomas, which showed significant expression in 27% and 9% of cases, respectively. In summary, SATB2 is a less sensitive marker of colorectal origin in mCRC compared with conventional CRC and shows significantly reduced specificity in mucinous gastroesophageal and breast primaries. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.