Gastric adenocarcinoma with enteroblastic differentiation followed endoscopically: A case report.

A 70-year-old man underwent endoscopy, which revealed a slightly depressed and elevated gastric cancer with suspected submucosal invasion of the mid gastric body. Biopsy specimens revealed differentiated tubular adenocarcinoma. We also detected lung and esophageal cancer and prioritized treatment of these lesions, and the patient underwent three endoscopies to monitor changes in gastric cancer. The tumor size and color remained unchanged; however, the marginal ridge was prominent, and the depressed area was deeper on subsequent evaluation. Total gastrectomy was performed 9 months after the first endoscopy. Histopathological examination of the resected specimens showed muscularis propria invasion, well-differentiated tubular adenocarcinoma involving the superficial mucosa, and tumor cells showing clear cytoplasm and a columnar or three-dimensional structure, between the deep mucosa and submucosa. The cells were immunopositive for Sal-like protein 4 and glypican 3; therefore, the patient was diagnosed with gastric adenocarcinoma with enteroblastic differentiation (GAED). This rare gastric cancer variant constituted approximately 70% of the entire lesion, and we observed significant lymphovascular invasion and lymph node metastasis. GAED is a rare histopathological subtype of gastric cancer described in recent years. Few cases of this tumor are reported to date; therefore, our study significantly contributes to the literature.