Abstract Background Gastric duplication cyst associated with ectopic pancreas is rare and we aimed to alert clinician to this congenital anomaly. Case presentation A 15-year-old girl presented with intermittent vomiting. Gastroscopy showed a submucosal tumor with an approximate diameter of 40 mm in the anterior wall of the gastric antrum. The lesion had a central umbilication and was diagnosed preliminarily as gastric ectopic pancreas with pseudocyst formation on the basis of its appearance. However, computed...