PMC5559920_01
Esophagogastroduodenoscopy (EGD) and endoscopic ultrasound (EUS) of the gastric mass. (a)-(b) EGD shows the 3.5 x 2.5 x 1.5 cm subepithelial gastric mass with central umbilication (blue arrow). (c)-(d) EUS shows the gastric mass is hypoechoic (blue arrow).
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fig1
An EGD with endoscopic ultrasound was performed at our institution, which redemonstrated the 3.5 cm subepithelial hypoechoic gastric mass that appeared to arise from the gastric muscular wall with central umbilication and ulceration (Figures 1(a)-1(d)).
Histologic H&E stained total gastrectomy. (a) Well-demarcated, poorly differentiated carcinoma with an organoid growth pattern and pushing borders ((a) 20x; (b) 100x). (c) High power view of organoid growth pattern and abundant peritumoral lymphocytic response (400x).
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The gastric resection specimen contained a well-circumscribed, poorly differentiated carcinoma with an organoid growth pattern and pushing borders centered on the muscularis propria (Figures 2(a)-2(b)). There was an abundant peritumoral lymphocytic response (Figure 2(c)).
Mismatch repair protein expression immunohistochemical profile (100x). The gastric medullary carcinoma is located at the bottom half of each field, while the overlying unremarkable gastric mucosa is located at the top portion of each field. (a) Loss of MLH1 expression. (b) Loss of PMS2 expression. (c) Intact MSH2 expression. (d) Intact MSH6 expression.
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The invasive tumor cells demonstrated loss of normal MLH1 (Figure 3(a)) and PMS2 (Figure 3(b)) protein expression, with retention of normal MSH2 (Figure 3(c)) and MSH6 (Figure 3(d)) protein expression.