Adenocarcinoma Around the Esophagogastric Junction Mimicking Submucosal Tumors: A Case Report.

An 81-year-old man with a branch-type intraductal papillary neoplasm underwent endoscopic evaluation for dysphagia, leading to the assessment of esophageal candidiasis, esophageal stenosis around the esophagogastric junction, and no malignant findings on the esophageal and gastric mucosae. Computed tomography (CT) showed a submucosal tumor. Endoscopic ultrasound (EUS) of the presumed submucosal tumor showed a well-circumscribed mass with internal punctate high echoes and enhanced posterior echoes. Major parts of the mass showed yellow-green to red on endoscopic elastography. EUS-guided core needle biopsy pathologically showed atypical epithelial cells with cuboidal structures and stromal reaction, leading to the diagnosis of adenocarcinoma. The patient, therefore, underwent robotic-assisted proximal gastrectomy and lymph node dissection. Postoperative pathological study showed the positive nodes in the lower para-esophageal and right cardia lymph nodes and atypical cells growing mainly in a tubular fashion which lacked mucosal malignancy, penetrated beyond the muscular propria, and spread widely under the esophageal and gastric mucosae. Immunostaining was negative for HER-2, PD-L1, CLDN12, and MSI. The patient recovered uneventfully, was discharged on the 13th day after surgery, and is scheduled to be followed up on an outpatient basis without adjuvant chemotherapy due to his old age. Diagnostic physicians should note that gastric submucosal tumors with intact gastric mucosae and all with circumscribed margins, internal high echoes, and enhanced posterior echoes on EUS suggest the possible well-differentiated adenocarcinomas arising from ectopic gastric glands in the stomach.