Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.
Mod Pathol. 2013 Jun;26(6):860-7. doi: 10.1038/modpathol.2012.226. Epub 2013 Jan 25.
A single, recurrent somatic point mutation (402C→G) in FOXL2 has been described in almost all adult-type granulosa cell tumors but not other ovarian neoplasms. Histopathological features of adult-type granulosa cell tumors can be mimicked by a variety of other tumors, making diagnosis of adult-type granulosa cell tumor challenging. It has been suggested that molecular testing for FOXL2 mutation might be a useful tool in the diagnosis of adult-type granulosa cell tumors. The aim of this study was to demonstrate how testing for the FOXL2 mutation can be used in a gynecological pathology consultation service and to establish clear procedural guidelines for FOXL2 testing. Immunohistochemistry for FOXL2 was done using an anti-FOXL2 polyclonal antiserum. If immunohistochemistry was positive, FOXL2 mutation status was subsequently analyzed using a TaqMan assay. A dilution experiment was done to assess the sensitivity and minimum tumor cellularity requirements for our TaqMan assay. Twenty problematic cases were assessed, where the differential diagnosis after the initial investigations included adult-type granulosa cell tumors. Differential diagnoses included: thecoma, Sertoli-Leydig cell tumor, juvenile granulosa cell tumor, endometrial stromal sarcoma and others. In all cases, FOXL2 immunohistochemistry was positive and in six samples the FOXL2 mutation was detected, thus confirming a diagnosis of adult-type granulosa cell tumor. The TaqMan assay was able to reliably detect the FOXL2 mutation with input DNA in the range of 2.5-20 ng, and with a minimum of 25% tumor cell nuclei. The analysis of the FOXL2 mutational status in clinical samples is a useful diagnostic tool in situations where the differential diagnosis is between adult-type granulosa cell tumor and other ovarian tumors. The TaqMan assay requires a minimum of 2.5 ng DNA, with optimal assay performance for 5 to 10 ng DNA input. Laser capture or needle-macrodissection should be undertaken to enrich samples with tumor cell content below 25%.
FOXL2 中的单个、反复出现的体突变（402C→G）已在几乎所有成人型颗粒细胞瘤中被描述，但在其他卵巢肿瘤中不存在。成人型颗粒细胞瘤的组织病理学特征可被多种其他肿瘤模仿，使成人型颗粒细胞瘤的诊断具有挑战性。有人提出，FOXL2 突变的分子检测可能是诊断成人型颗粒细胞瘤的有用工具。本研究旨在展示如何在妇科病理学咨询服务中使用 FOXL2 突变检测，并为 FOXL2 检测制定明确的程序指南。使用抗 FOXL2 多克隆抗血清进行 FOXL2 免疫组织化学检测。如果免疫组织化学阳性，则随后使用 TaqMan 分析 FOXL2 突变状态。进行稀释实验以评估我们的 TaqMan 分析的敏感性和最小肿瘤细胞含量要求。评估了 20 例有问题的病例，在初始检查后，这些病例的鉴别诊断包括成人型颗粒细胞瘤。鉴别诊断包括：卵泡膜细胞瘤、Sertoli-Leydig 细胞瘤、幼年型颗粒细胞瘤、子宫内膜间质肉瘤等。在所有情况下，FOXL2 免疫组织化学均为阳性，在 6 个样本中检测到 FOXL2 突变，从而证实了成人型颗粒细胞瘤的诊断。TaqMan 分析能够可靠地检测 FOXL2 突变，输入 DNA 的范围为 2.5-20ng，并且需要至少 25%的肿瘤细胞核。在鉴别诊断为成人型颗粒细胞瘤和其他卵巢肿瘤的情况下，分析 FOXL2 突变状态是一种有用的诊断工具。TaqMan 分析需要至少 2.5ng DNA，最佳检测性能为 5-10ng DNA 输入。应进行激光捕获或针式宏观切割，以富集肿瘤细胞含量低于 25%的样本。
