Loss of HER2 Positivity after Trastuzumab in HER2-Positive Gastric Cancer: Is Change in HER2 Status Significantly Frequent?

Figure 2

Microscopic findings of gastric cancer. (a) and (b) show biopsy specimens at presentation. (a) Histological findings show a well-differentiated tubular adenocarcinoma (hematoxylin and eosin staining, original magnification ×40). (b) Immunohistological findings of HER2 immunostaining show strong basolateral membrane reactivity with heterogeneity. The gastric cancer is scored as 3+ by HER2 immunohistochemistry scoring criteria (original magnification ×40). (c) and (d) show the resected specimen after chemotherapy including trastuzumab. (c) Histological findings show a moderately differentiated tubular adenocarcinoma invading into the subserosa (hematoxylin and eosin staining, original magnification ×40). (d) Immunohistological findings of HER2 immunostaining showed no membranous reactivity in any tumor cells (original magnification ×40).

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