FOXL2 Mutation is Absent in Uterine Tumors Resembling Ovarian Sex Cord Tumors. Am J Surg Pathol. 2015,[Epub ahead of print]
Uterine tumors resembling ovarian sex cord tumors (UTROSCTs) are rare uterine neoplasms characterized by pure or predominant epithelial-like patterns that share morphologic, immunohistochemical, and ultrastructural features with ovarian sex cord tumors. FOXL2 immunoexpression has recently been found in sex cord stromal tumors of the ovary, including granulosa cell tumors, Sertoli-Leydig cell tumors, thecomas, and fibromas, but mutations have been identified mostly in adult granulosa cell tumors. In this study, we investigated FOXL2 mutation status and protein expression in UTROSCTs. Mutational analysis using a TaqMan real-time polymerase chain reaction-based allelic discrimination assay was performed on formalin-fixed, paraffin-embedded tissue from 15 UTROSCTs. FOXL2 mutation was absent in all tumors. FOXL2 immunoexpression was tested in all 15 tumors. Intensity of staining was scored as weak, moderate, or strong. Percentage of tumor cells with nuclear staining was recorded as follows: 0 (negative); 1+ (1% to 25%); 2+ (26% to 50%); 3+ (51% to 75%); and 4+ (76% to 100%). Nuclear expression of FOXL2 was present in 6 of 15 (40%) UTROSCTs. One tumor demonstrated strong 4+ staining. Moderate expression was seen in 3 cases, including 2 and 1 showing 2+ and 1+ staining, respectively. Weak expression was observed in 2 tumors demonstrating 3+ and 1+ staining. Although UTROSCTs show overlapping morphologic, immunohistochemical, and ultrastructural features with sex cord stromal tumors of the ovary, they do not harbor FOXL2 mutation despite focal immunoreactivity in a subset of these tumors.

类似于卵巢性索肿瘤的子宫肿瘤(UTROSCTs)极其少见，完全或绝大部分以上皮样结构模式为特征，在形态学、免疫表型和超微结构上与卵巢性索肿瘤相似。最近研究发现FOXL2在卵巢性索间质肿瘤中有表达，包括颗粒细胞瘤、Sertoli-Leydig细胞瘤、thecomas和纤维瘤；而通常在成人型颗粒细胞瘤中存在其突变。本文作者在UTROSCTs中研究了FOXL2突变状况和蛋白表达情况。突变分析采用以TaqMan实时聚合酶链反应为基础的等位基因分型测定法，对15例经福尔马林固定、石蜡包埋的UTROSCTs组织进行了研究。结果显示：所有肿瘤中均缺乏FOXL2突变，然而均检测到了FOXL2的免疫表达。着色强度评分为弱阳性、中等强度阳性和强阳性；根据肿瘤细胞核标记阳性百分比分：阴性为0、1%～25%为1+、26%～50%为2+、51%～75%为3+、76%～100%为4+。6/15(40%)UTROSCTs细胞核表达FOXL2，其中1例为4+的强阳性着色；3例为中等强度阳性着色，其中2例为2+，1例为1+；2例为弱阳性着色，分别为3+和1+。以上结果表明尽管UTROSCTs在形态学、免疫表型和超微结构特征上与卵巢性索间质肿瘤有重叠，虽然这些肿瘤免疫组化可以表达FOXL2，然而其不存在FOXL2突变。