Abstract：
Knowing the sensitivity and specificity of tissue-specific immunohistochemical markers is crucial for accurate determination of the primary tumor site. PAX8 has been used as a diagnostic marker for carcinomas of the gynecologic tract, kidney, and thyroid gland, and CDX2 has been used as a marker of gastrointestinal carcinoma. Neither is considered a marker for breast carcinoma (BC). However, we have encountered BCs that express PAX8 or CDX2, some of which caused diagnostic confusion. We investigated the immunohistochemical staining frequency of PAX8 and CDX2 in BC. We identified 237 BCs for which PAX8 staining results were reported (102 primary and 135 metastatic BCs); seven primary and four metastatic BCs (4.6%) were positive for PAX8, with various intensities and staining patterns. CDX2 staining results were reported for 271 BCs (78 primary and 193 metastatic); four primary BCs and one metastatic BC (1.8%) were positive for CDX2, ranging from focal and weak to diffuse and strong. We also stained primary invasive BCs with PAX8 and CDX2 using tissue microarrays. None of the 332 PAX8-stained cases was positive, while one of 143 CDX2-stained cases was positive. Four PAX8-positive and three CDX2-positive cases were stained with TRPS1, and all were positive for TRPS1. In addition, we reviewed the literature for PAX8 and CDX2 expression in BCs and found 5.5% PAX8-positive BCs (90/1625) in 17 studies and 0.8% CDX-2 positive BCs (7/909) in 20 studies. PAX8 and CDX2 are infrequently expressed in BC by immunohistochemistry, and in rare cases, the staining can be strong and diffuse. Additional diagnostic markers are necessary and helpful in distinguishing breast from other primary origins.
摘要：
了解组织特异性免疫组织化学标记的敏感性和特异性对于准确确定原发肿瘤部位至关重要。PAX8已被用作妇科肿瘤的诊断标志物，肾,和甲状腺，CDX2已被用作胃肠道癌的标志物。两者都不被认为是乳腺癌（BC）的标志物。然而,我们遇到过表达PAX8或CDX2的BCs,其中一些引起诊断混乱.我们调查了BC中PAX8和CDX2的免疫组织化学染色频率。我们确定了237个报告了PAX8染色结果的BC（102个原发性和135个转移性BC）；7个原发性和4个转移性BC（4.6％）对PAX8呈阳性，具有各种强度和染色模式。据报道，271个BC（78个原发性和193个转移性）的CDX2染色结果；4个原发性BC和1个转移性BC（1.8％）的CDX2阳性，范围从局灶性和弱到弥漫性和强。我们还使用组织微阵列用PAX8和CDX2对原发性侵袭性BCs进行染色。332例PAX8染色病例均无阳性，143例CDX2染色病例中有1例呈阳性。4例PAX8阳性和3例CDX2阳性病例用TRPS1染色,且均为TRPS1阳性。此外,我们回顾了有关BCs中PAX8和CDX2表达的文献,发现17项研究中有5.5%的PAX8阳性BCs(90/1625),20项研究中有0.8%的CDX-2阳性BCs(7/909).通过免疫组织化学，PAX8和CDX2在BC中很少表达，在极少数情况下，染色可以是强的和弥漫性的。额外的诊断标记是必要的，并且有助于将乳腺与其他主要来源区分开。
