has part has part characteristic of part of has modifier Abnormal esophagus morphology Gastrointestinal duplication Esophageal duplication Esophageal duplication is a rare cause of mediastinal mass. An esophageal duplication may be a simple epithelial cyst or duplication that contains muscle and submucosa but not epithelium. In most cases, the duplication is located in the lower third of the esophagus, and the most common associated symptom is difficulty in swallowing. Esophageal duplication occurs because of maldevelopment of the posterior division of embryonic foregut. abnormal duplicated esophagus