We herein report two extremely rare cases of gastric adenocarcinoma with enteroblastic differentiation (GAED) that underscore the aggressive nature of GAED. Case 1: ESD was scheduled for early-stage gastric cancer, however, the tumor increased in size drastically and the morphology changed to type "0-I + IIc" in one month. Surgery was performed and the patient was diagnosed with GAED. Case 2: ESD was performed for early-stage gastric cancer, and the pathological findings revealed GAED. The horizontal margin was positive for clear cells in the muscularis mucosa. Additional surgery was performed; however, recurrence occurred one year later. Therefore, the treatment strategies should be carefully considered for GAED.
Keywords: Sal-like protein 4; alpha fetoprotein; gastric adenocarcinoma with enteroblastic differentiation; glypican3.