A potential pitfall in evaluating HER2 immunohistochemistry for gastric signet ring cell carcinomas

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• 作者：Chang Gok Woo¹ ; ^&lowast ; ; Won Jin Ho² ; ^&lowast ; ; Young Soo Park³ ; ^{youngspark@amc.seoul.kr} ; Sook Ryun Park⁴ ; Min-Hee Ryu⁴ ; Hwoon-Yong Jung⁵ ; Yoon-Koo Kang⁴
• 关键词：Gastric cancer ; signet ring cell carcinoma ; immunohistochemistry ; HER2 ; trastuzumab
• 刊名：Pathology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：49
• 期：1
• 页码：38-43
• 全文大小：1538 K
• 卷排序：49

文摘

Signet ring cell carcinoma (SRC) more commonly presents as metastatic disease and renders patients to be considered for chemotherapy. While treatment options are limited overall, trastuzumab has been shown to be effective for HER2 positive SRC cases. The current algorithm for HER2 evaluation heavily relies on positive membrane-specific staining by immunohistochemistry (IHC), but several anecdotal reports have suggested that SRCs may be susceptible to misinterpretation due to non-specific staining in the marginated cytoplasm with/without nucleus.Results of two FDA-approved IHC methods of HER2 evaluation, Pathway and HercepTest, along with silver in situ hybridisation were interpreted retrospectively and compared in 155 primary SRC cases.IHC results were discrepant between the two assays in SRC even at the strongest IHC scores. Discordance indeed occurred due to dark, non-specific staining obscured by the unique SRC morphology. True HER2 positive SRC was identified in three cases (3/155, 1.9%).In this study, we demonstrate the importance of recognising potential discrepancy in interpreting HER2 status depending on the assay used. Understanding this possible pitfall may prevent unnecessary trastuzumab in SRC patients.