We present a case of gastrointestinal duplication cyst of the stomach.

Our ultrasound revealed a 10 x 6 mm cyst in the upper abdomen of the fetus, adjacent to the fetal stomach (Images 1 and 2). We were concerned for a double bubble sign, thus performed amniocentesis, which was normal. On subsequent ultrasounds, the finding appeared to be a cyst protruding into the lumen of the stomach. We therefore obtained fetal MRI to better define the cyst origin and relationship with adjacent organs. T2-weighted sequences showed a round, well-circumscribed, hyperintense 1 cm mass without communication with gastric lumen, below the diaphragm and adjacent to the gastric fundus / gastro-esophageal junction (Images 3 and 4). The other abdominal organs appeared to be normal. Our differential diagnosis included omental, mesenteric, choledochal, and neurenteric cysts.

Discussion

Duplication cysts constitute a rare group of malformations that can occur anywhere along the gastrointestinal tract. Gastric duplications cysts account for 4% of all enteric duplications, approximately 17 cases per million births. In our case, prenatal MRI was helpful in the diagnosis.

Gastrointestinal duplications are tubular or cyst structures composed of intestinal mucosa and muscle that are usually closely adherent to some part of the gastrointestinal tract. Their mucosa is often similar to that of the portion of bowel to which it is attached, and the lumen is generally cystic due to the secretion of clear fluid by the mucosal cells. Approximately 75% of duplication cysts are located within the abdominal cavity, while the remaining are intrathoracic (20%) or thoracoabdominal (5%). Seventy five percent of duplications are considered cystic, without communication to adjacent intestine, while the remaining are cylindrical structures that may or may not have one or more direct communications across the common septum.

Gastric duplications are typically non-communicating cystic structures located along the greater curvature or antrum, and are more rarely reported at the level of the pylorus. Usually they present as a cyst in the upper abdomen, which may vary in length from a few to several centimeters. Ultrasound may reveal the inner echogenic mucosa and outer hypoechoic muscle layers that are typical of a gastrointestinal tract duplication, though it can be difficult to visualize in prenatal examinations.

An MRI can confirm the presumptive ultrasound diagnosis, providing additional information on the location and relationship with other organs, thus contribute to treatment planning.