Immunohistochemical markers shown to be useful in identifying/confirming mesonephric/mesonephric-like differentiation (MLD markers) include thyroid transcription factor (TTF1), GATA-binding protein 3 (GATA3), and cluster of differentiation 10 (CD10). Only a few studies have examined the expression levels of MLD markers in endometrial endometrioid carcinomas (EECs). This study aimed to analyze the frequency and pattern of MLD marker expression in low-grade EECs. We performed immunostaining for the detection of TTF1, GATA3, and CD10 expression in 50 low-grade EEC tissue samples and evaluated their staining proportion and intensity. Nine tumors (18.0%) expressed at least one MLD marker in varying proportions and intensities, and 2 of these tumors were positive for 2 MLD markers (TTF1/GATA3 and GATA3/CD10, respectively). Three (6.0%) tumors showed moderate-to-strong nuclear TTF1 immunoreactivity in ≤5% of the tumor cells. Five tumors (10.0%) had at least moderate nuclear GATA3 staining, and three of them displayed a staining proportion of ≥15%. Three tumors (6.0%) were focal (mean proportion, 15%) but strongly positive for CD10. Our findings indicate that a subset of EEC can express one or more MLD markers with varying staining proportions and intensities. Given that a diagnosis of uterine mesonephric-like adenocarcinoma should be established based on a combination of characteristic histologic features, unique immunophenotypes, and confirmed molecular findings, pathologists should not exclude EEC based only on the presence of focal immunoreactivity for MLD markers. Awareness of the atypical expression patterns of MLD markers in EEC helps pathologists avoid misdiagnosing EEC as a uterine mesonephric-like adenocarcinoma.

中文翻译：

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低级别子宫内膜样癌中肾标记物表达的综合免疫组织化学分析。

已证明可用于识别/确认中肾/中肾样分化（MLD 标记）的免疫组织化学标记物包括甲状腺转录因子 (TTF1)、GATA 结合蛋白 3 (GATA3) 和分化簇 10 (CD10)。只有少数研究检测了子宫内膜样子宫内膜癌 (EEC) 中 MLD 标记物的表达水平。本研究旨在分析低级别 EEC 中 MLD 标记表达的频率和模式。我们对50份低级别EEC组织样本中的TTF1、GATA3和CD10表达进行了免疫染色检测，并评估了它们的染色比例和强度。9 个肿瘤 (18.0%) 以不同比例和强度表达至少一种 MLD 标记物，其中 2 个肿瘤对 2 种 MLD 标记物呈阳性（分别为 TTF1/GATA3 和 GATA3/CD10）。三个 (6.0%) 肿瘤在 ≤5% 的肿瘤细胞中表现出中度至强的核 TTF1 免疫反应性。5 个肿瘤（10.0%）具有至少中度的核 GATA3 染色，其中 3 个肿瘤的染色比例≥15%。三个肿瘤 (6.0%) 为局灶性肿瘤（平均比例为 15%），但 CD10 呈强阳性。我们的研究结果表明，EEC 的一个子集可以表达一种或多种具有不同染色比例和强度的 MLD 标记。鉴于子宫中肾样腺癌的诊断应基于特征性组织学特征、独特的免疫表型和已证实的分子发现的结合，病理学家不应仅根据 MLD 标记物局灶性免疫反应性的存在来排除 EEC。了解 EEC 中 MLD 标记的非典型表达模式有助于病理学家避免将 EEC 误诊为子宫中肾样腺癌。