Cervical esophageal adenocarcinoma of intestinal type in ectopic gastric mucosa

A 45‐year‐old man underwent esophagogastroduodenoscopy because of symptoms of laryngopharyngeal discomfort. We found a protruded reddish lesion adjacent to the ectopic gastric mucosa (EGM) in the cervical esophagus, and a biopsy revealed that it was a tubular adenocarcinoma. We diagnosed the patient with intramucosal cancer and performed endoscopic submucosal dissection. Esophageal endoscopic submucosal dissection was performed under general anesthesia using a conventional procedure. The resected tumor measured 23 × 14 mm and was adjacent to the EGM. Histologically, the tumor cells showed moderately well‐differentiated adenocarcinoma confined to the muscularis mucosa with no lymphovascular infiltration. Immunohistochemically, the tumor cells were positive for intestinal markers, namely MUC2 and CD10, and negative for gastric markers, namely MUC5AC and MUC6. The patient had no post‐endoscopy submucosal dissection stenosis and remained disease‐free without local recurrence. EGM of the cervical esophagus develops from the columnar epithelium during embryonic development. There are few reports on endoscopic submucosal dissection for mucosal cancer. Of these, immunostaining was performed in three cases. All were positive for MUC5AC and MUC6 and negative for MUC2 and CD10. Usually, EGM shows gastric type epithelium, but occasional cases with intestinal metaplasia, which show positivity for MUC2 and CD10, have been reported. Therefore, we consider this to be an extremely rare case of esophageal adenocarcinoma arising from intestinal metaplasia within the EGM.