Brief CommentaryOCT4: A Sensitive and Specific Immunohistochemical Marker for Metastatic Germ Cell TumorsLau, Sean K. MD; Chang, Karen L. MDAuthor Information Department of Pathology, City of Hope National Medical Center, Duarte, CA Reprints: Sean K. Lau, MD, City of Hope National Medical Center, Department of Pathology, 1500 East Duarte Road, Duarte, CA 91010 (e-mail: [email protected]). Advances in Anatomic Pathology: March 2006 - Volume 13 - Issue 2 - p 76-79 doi: 10.1097/01.pap.0000213011.33232.72 Buy Metrics Abstract Octamer-binding transcription factor 4 (OCT4) is a transcription factor normally expressed in embryonic stem cells and germ cells. Recent investigations have shown OCT4 to be a sensitive and specific immunohistochemical marker of gonadal germ cell tumors, specifically seminoma and embryonal carcinoma. Expanding on these previous studies, a recent report by Cheng evaluated the diagnostic utility of OCT4 immunohistochemistry in the identification of germ cell tumors in the metastatic setting. In this context, OCT4 was observed to be a highly reliable marker for metastatic germ cell tumors that contained components of seminoma or embryonal carcinoma. The results of this study indicate that OCT4 immunohistochemistry is a useful diagnostic tool for establishing the germ cell origin of a metastatic tumor and suggest a potential role for OCT4 in the immunohistochemical assessment of carcinomas of unknown primary origin. Copyright © 2006 Wolters Kluwer Health, Inc. All rights reserved.