Sex cord-stromal tumors (SCSTs) account for the second most common category of testicular neoplasms and include several entities that may show overlapping morphologies and present diagnostic challenges. We analyzed a cohort of 120 testicular SCSTs and investigated the diagnostic utility of SRY-box transcription factor 9 (SOX9), forkhead box protein L2 (FOXL2), and steroidogenic factor 1 (SF-1) immunohistochemical stains. The results were compared with the more commonly used SCST markers, inhibin α, calretinin, and Wilms' tumor 1 (WT1). SF-1 was overall the most sensitive stain (91%), followed by inhibin α (70%), calretinin (52%), FOXL2 (50%), SOX9 (47%), and WT1 (37%), but sensitivities varied by tumor type. SOX9 and calretinin were more commonly positive in sex cord elements versus stromal elements (62% vs. 27% and 47% vs. 9%, respectively), whereas FOXL2 was more commonly positive in stromal elements versus sex cord elements (100% vs. 55%) when excluding Leydig cell tumors from the stromal category. Although no individual stain was diagnostically specific, some immunophenotypic patterns were noted that may help in the subclassification of SCSTs. We conclude that SOX9, FOXL2, and SF-1 are useful immunohistochemical stains for confirming sex cord-stromal differentiation in testicular tumors and provide increased sensitivity as well as additional diagnostic information, especially when combined with the more commonly used inhibin α, calretinin, and WT1 immunostains. Although morphology is paramount for subclassification of SCSTs, knowledge of certain immunohistochemical patterns may be helpful for diagnostically challenging cases.

中文翻译：

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120 个睾丸性索间质肿瘤的免疫组织化学表征，重点是 SOX9、FOXL2 和 SF-1 的诊断效用。

性索间质肿瘤 (SCST) 是睾丸肿瘤的第二大常见类别，包括几个可能表现出重叠形态和诊断挑战的实体。我们分析了 120 个睾丸 SCST，并研究了 SRY 盒转录因子 9 (SOX9)、叉头盒蛋白 L2 (FOXL2) 和类固醇生成因子 1 (SF-1) 免疫组织化学染色的诊断效用。将结果与更常用的 SCST 标志物、抑制素 α、钙视网膜蛋白和维尔姆斯肿瘤 1 (WT1) 进行比较。SF-1 总体上是最敏感的染色剂 (91%)，其次是抑制素 α (70%)、钙视网膜蛋白 (52%)、FOXL2 (50%)、SOX9 (47%) 和 WT1 (37%)，但敏感性较低因肿瘤类型而异。SOX9 和钙视网膜蛋白在性索元素与基质元素中更常见阳性（分别为 62% 对 27% 和 47% 对 9%），而当从基质类别中排除 Leydig 细胞肿瘤时，FOXL2 在基质元素与性索元素中更常见阳性（100% 对 55%）。尽管没有单个染色具有诊断特异性，但注意到一些免疫表型模式可能有助于 SCST 的子分类。我们得出结论，SOX9、FOXL2 和 SF-1 是有用的免疫组织化学染色，可用于确认睾丸肿瘤中的性索间质分化，并提供更高的灵敏度和额外的诊断信息，尤其是与更常用的抑制素 α、钙调蛋白和WT1 免疫染色。尽管形态对于 SCST 的子分类至关重要，但了解某些免疫组织化学模式可能有助于诊断具有挑战性的病例。