Department of Pathology, Alpert Medical School of Brown University, Women and Infants Hospital of Rhode Island, Providence, RI.
Appl Immunohistochem Mol Morphol. 2020 Aug;28(7):558-561. doi: 10.1097/PAI.0000000000000796.
PAX8 is a specific marker for kidney, ovarian, and thyroid tissue. Antibody-dependent cross-reactivity for PAX8 has been reported in mesothelial, pancreatic, and B-cell proliferations. We recently described antibody clone-dependent aberrant PAX8 expression in breast cancer. In this study we systematically analyze PAX8 expression in breast cancer on whole tissue sections, using MRQ50 and BC12 PAX8 monoclonal antibodies. Immunohistochemistry was performed on formalin-fixed paraffin-embedded whole tissue sections from 85 invasive mammary carcinomas. Immunostaining was evaluated at ×10 objective; extent (intervals of 10%, 0% to 100%) and intensity (weak, moderate, and strong) of nuclear staining was evaluated in the tumor, benign breast tissue, and lymphocytes. With MRQ50 variable PAX8 nuclear positivity was identified in tumor cells in 35/85 (41%) cases. Of 35 PAX8 cases, 23 (66%) showed only weak expression in 1% to 10% cells, 8 (23%) were weakly (5/8) or moderately (3/8) PAX8 in 11% to 50% cells, and 4 (11%) showed weak PAX8 positivity in >50% tumor cells. All 3 (3.5%) cases that showed moderate nuclear PAX8 staining with MRQ50 were histologic grade 3. No PAX8 expression was noted in benign lobules/ducts with either antibody. Breast carcinomas can show nuclear immunostaining with MRQ50 PAX8 antibody with up to 3.5% cases showing moderately intense expression. The BC12 PAX8 antibody does not cross-react with breast carcinoma and lymphocytes. During workup of metastatic carcinoma, weak to moderate PAX8 nuclear expression with MRQ50 clone should be interpreted with caution.
PAX8 是肾脏、卵巢和甲状腺组织的特异性标志物。已经报道 PAX8 抗体依赖性交叉反应存在于间皮细胞、胰腺和 B 细胞增生中。我们最近描述了在乳腺癌中抗体克隆依赖性异常 PAX8 表达。在这项研究中，我们使用 MRQ50 和 BC12 PAX8 单克隆抗体，在整个组织切片上系统地分析乳腺癌中的 PAX8 表达。对 85 例浸润性乳腺腺癌的福尔马林固定石蜡包埋全组织切片进行免疫组织化学染色。在肿瘤、良性乳腺组织和淋巴细胞中，对核染色的程度（间隔 10%，0%至 100%）和强度（弱、中、强）进行评估。在 35/85（41%）例肿瘤细胞中，MRQ50 显示出可变的 PAX8 核阳性。在 35 例 PAX8 病例中，23 例（66%）在 1%至 10%的细胞中仅显示弱表达，8 例（23%）在 11%至 50%的细胞中显示弱（5/8）或中度（3/8）PAX8 表达，4 例（11%）在>50%的肿瘤细胞中显示弱 PAX8 阳性。在 MRQ50 中显示中度核 PAX8 染色的所有 3 例（3.5%）病例均为组织学 3 级。在任何一种抗体中，良性小叶/导管均未显示 PAX8 表达。乳腺癌可显示 MRQ50 PAX8 抗体的核免疫染色，多达 3.5%的病例显示中度强表达。BC12 PAX8 抗体与乳腺癌和淋巴细胞无交叉反应。在转移性癌的检查过程中，使用 MRQ50 克隆，对弱阳性至中度 PAX8 核表达应谨慎解释。
