Original ArticlesSMARCA4 (BRG1) Loss of Expression Is a Useful Marker for the Diagnosis of Ovarian Small Cell Carcinoma of the Hypercalcemic Type (Ovarian Rhabdoid Tumor) A Comprehensive Analysis of 116 Rare Gynecologic Tumors, 9 Soft Tissue Tumors, and 9 MelanomasKaranian-Philippe, Marie MD*,†,‡; Velasco, Valérie BSc*; Longy, Michel MD*; Floquet, Anne MD§; Arnould, Laurent MD∥; Coindre, Jean-Michel MD*,†,‡; Le Naoures-Méar, Cécile MD¶; Averous, Gerlinde MD#; Guyon, Frédéric MD**; MacGrogan, Gaëtan MD*,†; Croce, Sabrina MD*,†Author Information *Department of BioPathology §Medical Oncology **Surgery, Institut Bergonié †INSERM U916 ‡Université de Bordeaux, Bordeaux ∥Department of Pathology, Centre JF Leclerc, Comprehensive Cancer Centre, Dijon ¶Department of Pathology, University Hospital of Caen, Caen #Department of Pathology, University Hospital of Strasbourg, Strasbourg, France 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: Sabrina Croce, MD, Department of BioPathology, Institut Bergonié, 229 cours de l′Argonne, F-33000 Bordeaux Cedex, France (e-mail: firstname.lastname@example.org). The American Journal of Surgical Pathology: September 2015 - Volume 39 - Issue 9 - p 1197-1205 doi: 10.1097/PAS.0000000000000475 Buy Metrics Abstract Ovarian small cell carcinoma of the hypercalcemic type (SCCOHT)/ovarian rhabdoid tumor is a rare and highly malignant tumor that typically occurs in young women. Up until now the diagnosis has been made on the basis of morphology without any specific immunohistochemical (IHC) markers. However, several authors have shown recently that SCCOHTs are characterized by inactivation of the SMARCA4 gene (encoding the BRG1 protein) resulting in a loss of BRG1 protein expression in IHC. We evaluated BRG1 and INI1 expression in 12 SCCOHTs and in a series of 122 tumors that could mimic SCCOHT morphologically: 9 juvenile granulosa cell tumors, 47 adult granulosa cell tumors, 33 high-grade ovarian serous carcinomas, 9 desmoplastic round cell tumors, 13 Ewing sarcomas (5 from the pelvis and 8 from soft tissues), 1 round cell sarcoma associated with CIC-DUX4 translocation from soft tissue (thigh), 1 case of high-grade endometrial stromal sarcoma of the ovary, and 9 melanomas. Forty-four adult granulosa cell tumors were interpretable by IHC. All 12 SCCOHTs were devoid of BRG1 expression and expressed INI1. All other interpretable 119 tumors showed BRG1 nuclear positivity, with variable staining proportions, ranging from 10% to 100% of positive cells (mean: 77%, median: 80%), variable intensities (weak: 5%, moderate: 37%, strong: 58%), and distributions: diffuse in 82 cases (70%) and heterogenous in 36 cases (30%). BRG1 positivity was heterogenous in desmoplastic round cell tumors and adult granulosa cell tumors. Overall, BRG1 is a useful diagnostic marker in SCCOHT, showing the absence of expression in SCCOHT. Nevertheless, the possible heterogeneity and the variable intensity of this staining warrant caution in the interpretation of BRG1 staining in biopsy specimens. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.