成年颗粒细胞瘤 (AGCT)是一种分子上独特的恶性卵巢性索-间质肿瘤 (SCST) 组，其特征是在FOXL2基因中存在一种近乎普遍的c.402C>G/p.C134W突变，下文简称为"C134W"。在某些情况下，AGCT在形态上与其他SCST有很大的重叠性，并且具有相同的免疫表型，因此可能需要分子检测来帮助确诊。然而，分子检测耗时、相对昂贵，并且许多病理实验室无法提供此项服务。我们描述了一个用于检测FOXL2 C134W突变的原位杂交 (ISH) 定制BaseScope分析的开发和验证过程。我们评估了106例卵巢SCST，其中包括78例AGCT，9例少年颗粒细胞瘤，18例纤维瘤（细胞型和常规型），以及1例未特指的SCST，以及53例上皮性卵巢肿瘤（42例子宫内膜样癌和11例肉瘤样癌）和1例STK11附属器官肿瘤，通过Basescope-ISH检测FOXL2野生型和FOXL2 C134W的RNA表达情况。其中51个肿瘤已经接受了FOXL2基因的DNA测序。整个队列中，FOXL2 C134W探针染色在77/78 (98.7%) AGCT中呈阳性。2/81 (2.5%) 非AGCT也显示阳性染色，均为上皮性卵巢肿瘤。该分析可以用于超过20年的组织块。 FOXL2测序和Basescope-ISH结果完全一致。总体而言，通过定制的Basescope-ISH评估FOXL2突变状态对于AGCT的诊断显示具有98.7%的敏感性和97.5%的特异性。 FOXL2 C134W的Basescope-ISH代表了测序的合理替代方法，速度更快、成本更低，并且比分子检测更容易应用于许多病理实验室中。它还具有需要较少组织的优势，并且肿瘤细胞可以在染色切片上直接可视化。版权所有 © 2023. 由Elsevier Inc.出版。

Adult granulosa cell tumors (AGCT) are a molecularly distinct group of malignant ovarian sex cord-stromal tumors (SCST) characterized by a nearly ubiquitous c.402C>G/p.C134W mutation in FOXL2 (hereafter referred to as "C134W"). In some cases, AGCT exhibits marked morphological overlap with other SCSTs, and have an identical immunophenotype, and molecular testing may be necessary to help confirm the diagnosis. However, molecular testing is time-consuming, relatively expensive, and unavailable in many pathology laboratories. We describe the development and validation of an in situ hybridization (ISH) custom BaseScope assay for the detection of the FOXL2 C134W mutation. We evaluated 106 ovarian SCSTs, including 78 AGCT, 9 juvenile granulosa cell tumors, 18 fibromas (cellular and conventional), and 1 SCST, not otherwise specified (NOS), as well as 53 epithelial ovarian tumors (42 endometrioid carcinomas and 11 carcinosarcomas) and 1 STK11 adnexal tumor for the presence or absence of FOXL2 wild-type and FOXL2 C134W RNA expression via Basescope-ISH. Fifty-one tumors had previously undergone DNA sequencing of the FOXL2 gene. Across the entire cohort, the FOXL2 C134W probe staining was positive in 77/78 (98.7%) AGCTs. 2/81 (2.5%) non-AGCT also showed positive staining, both of which were epithelial ovarian tumors. The assay worked in tissue blocks >20 years old. There was 100% concordance between the FOXL2 sequencing and Basescope-ISH results. Overall, assessment of FOXL2 mutation status by custom Basescope-ISH demonstrated 98.7% sensitivity and 97.5% specificity for the diagnosis of AGCT. Basescope-ISH for FOXL2 C134W represents a reasonable alternative to sequencing, is quicker and less expensive, and is more easily incorporated than molecular testing into many pathology laboratories. It also has the advantage of requiring less tissue, and the neoplastic cells can be directly visualized on stained sections.Copyright © 2023. Published by Elsevier Inc.