Original ArticlesGATA3 Positivity in Benign Radiated Prostate Glands A Potential Diagnostic PitfallWobker, Sara E. MD, MPH; Khararjian, Armen MD, MBA; Epstein, Jonathan I. MDAuthor Information *Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC Departments of †Pathology ‡Urology §Oncology, The Johns Hopkins Medical Institutions, Baltimore, MD Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article Correspondence: Jonathan I. Epstein, MD, Department of Pathology, The Johns Hopkins Medical Institutions, 401 N. Broadway, Weinberg Building, Room 2242, Baltimore, MD 21231 (e-mail: firstname.lastname@example.org). The American Journal of Surgical Pathology: April 2017 - Volume 41 - Issue 4 - p 557-563 doi: 10.1097/PAS.0000000000000798 Buy Metrics Abstract Histologic changes following radiation therapy to the prostate include multilayering of glands, atrophy, squamous metaplasia, and often marked random nuclear atypia. We have seen multiple consultation cases where the differential diagnosis of these radiated prostate glands included urothelial carcinoma, with multilayered to solid-appearing proliferations that were positive by immunohistochemistry for GATA3. To formally investigate this issue, 30 cases of benign prostate tissue with radiation atypia, from 1990 to 2015, were obtained from our institution. Cases were evaluated by immunohistochemistry for the prostate-specific markers prostate-specific antigen (PSA), P501S (Prostein), and NKX3.1 and urothelial markers GATA3 and uroplakin 2. GATA3 was positive in 100% of cases, with 70% showing moderately strong to strong staining in a mostly patchy manner within a gland. PSA was positive in 93.3% of cases, with 89.2% showing moderately strong to strong staining in a mostly diffuse manner. P501S was positive in 96.7% of cases, with 93.1% showing moderately strong to strong staining in a mostly patchy manner. NKX3.1 was positive in 82.8% of cases, with 33.3% showing moderately strong to strong staining in a mostly patchy manner. Uroplakin 2 was negative in 100% of cases. Our findings highlight that GATA3 is often positive in benign prostate glands with radiation atypia, which along with the morphologic features present a pitfall for the misdiagnosis of urothelial carcinoma. A combination of PSA and P501S is the best prostate-specific panel for use in radiated prostate, with the caveat that they are often patchy and do not stain all radiated glands. Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.