Foregut duplication cyst of the stomach with pseudostratified columnar ciliated epithelium

Duplication cyst of the stomach with pseudostratified columnar ciliated epithelium is extremely rare. A 72‐year‐old Japanese woman visited Oomoto Hospital for examination of the stomach. Gastroendoscopy indicated a slightly depressed gastric cancer in the anterior wall of the middle third of the stomach. Adenocarcinoma was confirmed on endoscopic biopsy. Preoperative CT indicated a subserosal cystic lesion 2 cm in diameter on the lesser curvature of the stomach. The cystic lesion was resected through distal gastrectomy and systematic lymph node dissection. Histopathology showed that the cyst did not communicate with the gastric lumen, had pseudostratified columnar ciliated epithelium with circular muscle layers, and did not have gastric epithelium or cartilaginous tissue. The gastric cancer consisted of moderately differentiated adenocarcinoma with submucosal invasion and lymph node metastasis. Consequently, the present patient was diagnosed as having foregut duplication cyst of the stomach.