Intrinsic masses in the stomach of infants and children are exceedingly rare. Pressure defects on the stomach are occasionally seen from an enlarged spleen or liver. This communication presents four uncommon entities causing displacement or pressure defects: duplication of the stomach, pseudocyst of the pancreas, a left-sided gallbladder, and a solitary cyst of the left lobe of the liver. The surgical consideration for each of these disorders is different; therefore, it is important to establish the correct diagnosis preoperatively. Since a mass in the epigastrium is uncommon in children, roentgenographic studies are most helpful in confirming the lesion and showing its relationship to intraabdominal viscera. Duplication of the Stomach Duplications of the alimentary canal are spherical or tubular structures, lined by mucous membrane, with a well developed muscular wall. While the lining epithelium resembles some portion of the gastrointestinal tract, the mucosa of the duplicate structure may be quite different from that of the normal bowel to which it is related. Duplications may be found anywhere from the base of the tongue to the rectum, but those involving the stomach are the rarest (8). Despite the fact that these are congenital anomalies, symptoms often are not evident until adult life (7). When symptoms of gastric duplication have been present, obstruction of the gastric antrum, bleeding from ulcerated mucosa in the duplication, epigastric pain, and a palpable epigastric mass have been the most common findings. In the infant the obstruction may mimic hypertrophic pyloric stenosis (13) or present as a thoracic mass, possibly connected to the spinal cord by a persistence of the neurenteric canal. Although these duplications may occur anywhere along the greater curvature of the stomach, they are usually in the region of the antrum. The most common is a blind pouch attached to a portion of the normal intestinal tract. This noncommunicating type is generally filled with fluid and causes a smooth indentation of the adjacent structures (Fig. 1). The duplication may be outlined by the barium in cases in which a communication exists with the stomach. Choledochal cysts cause widening of the duodenal sweep and may produce pressure defects on the antrum of the stomach; cholangiography may be helpful in differentiating these. Antral deformity and pyloric obstruction have been seen with hematomas secondary to trauma and in patients with hemophilia; in such cases the history would lead to the proper diagnosis. Massive hydrops of a normally positioned gallbladder produced pyloric obstruction in a seven-year-old boy (10). A nonfunctioning gallbladder with normal ducts would suggest the proper diagnosis. The pathogenesis for duplication of the stomach is less well understood than for duplication of the small and large bowel.