Special Article: PDF OnlyReport From the International Society of Urological Pathology (ISUP) Consultation Conference on Molecular Pathology of Urogenital Cancers IV Current and Future Utilization of Molecular-Genetic Tests for Testicular Germ Cell TumorsLooijenga, Leendert H.J. PhD*; Van der Kwast, Theodorus H. MD, PhD†; Grignon, David MD‡; Egevad, Lars MD§; Kristiansen, Glen MD∥; Kao, Chia-Sui MD¶; Idrees, Muhammad T. MD#Author Information *Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands †Laboratory Medicine Program, University Health Network, Toronto, Canada Departments of ‡Pathology and Laboratory Medicine #Pathology, Indiana University School of Medicine, Indianapolis, IN §Department of Oncology and Pathology, Karolinska Institutet Sweden, Solna, Sweden ∥Department of Pathology, University Hospital Bonn, Bonn, Germany ¶Department of Pathology, Stanford University School of Medicine, Stanford, CA C.-S.K. and M.T.I. shared last authorship. 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: Leendert H.J. Looijenga, PhD, Princess Máxima Center for Pediatric Oncology, Utrecht 3084 CS, The Netherlands (e-mail: email@example.com). The American Journal of Surgical Pathology: March 20, 2020 - Volume Publish Ahead of Print - Issue - doi: 10.1097/PAS.0000000000001465 Buy SDC PAP Metrics Abstract The International Society of Urological Pathology (ISUP) organized a Consultation Conference in March 2019 dealing with applications of molecular pathology in Urogenital Pathology, including testicular tumors (with a focus on germ cell tumors [GCTs]), preceded by a survey among its members to get insight into current practices in testicular germ cell tumor (TGCT) diagnostics and adoption of the ISUP immunohistochemical guidelines published in 2014. On the basis of the premeeting survey, the most commonly used immunomarker panel includes OCT3/4, placental alkaline phosphate, D2-40, SALL4, CD117, and CD30 for GCTs and the documentation of germ cell neoplasia in situ (GCNIS). Molecular testing, specifically 12p copy gain, is informative to distinguish non-GCNIS versus GCNIS related GCTs, and establishing germ cell origin of tumors both in the context of primary and metastatic lesions. Other molecular methodologies currently available but not widely utilized for TGCTs include genome-wide and targeted approaches for specific genetic anomalies, P53 mutations, genomic MDM2 amplification, and detection of the p53 inactivating miR-371a-3p. The latter also holds promise as a serum marker for malignant TGCTs. This manuscript provides an update on the classification of TGCTs, and describes the current and future role of molecular-genetic testing. The following recommendations are made: (1) Presence of GCNIS should be documented in all cases along with extent of spermatogenesis; (2) Immunohistochemical staining is optional in the following scenarios: identification of GCNIS, distinguishing embryonal carcinoma from seminoma, confirming presence of yolk sac tumor and/or choriocarcinoma, and differentiating spermatocytic tumor from potential mimics; (3) Detection of gain of the short arm of chromosome 12 is diagnostic to differentiate between non-GCNIS versus GCNIS related GCTs and supportive to the germ cell origin of both primary and metastatic tumors. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.