Causes of duodenal lymphatic dilatation include congenital digestive tract malformations, digestive tract tumors, superior mesenteric artery compression syndrome, compression by enlarged peripheral tissues, and duodenal diseases. 1. Congenital digestive malformations: for example, congenital stenosis of duodenum, congenital megacolon and congenital intestinal atresia, etc., which can cause obstruction of emptying of intestinal contents, cause intestinal obstruction and induce duodenal dilatation. 2. Tumor of digestive tract: such as stomach cancer, pancreatic cancer and duodenal tumor, etc., because the intestinal canal is compressed by the enlarged tumor, which leads to intestinal obstruction and duodenal dilatation. 3. Superior mesenteric artery compression syndrome: because the angle between the superior mesenteric artery and the abdominal aorta is relatively small, which can easily lead to narrowing of intestinal lumen, cause intestinal obstruction and induce duodenal dilatation. 4. Peripheral tissue enlargement and compression: for example, parasites accumulate into a block, inflammatory lesions in the small intestine and huge gallbladder stones, etc., all of which may lead to peripheral tissue compression and cause duodenal dilatation. 5. Duodenal diseases: such as Crohn’s disease and progressive systemic sclerosis, etc., can lead to the duodenum horizontal section or the upper part of the jejunum is compressed, and then cause duodenal dilatation. It is recommended that patients need to go to a regular hospital to receive further examination, according to the results of the examination, treatment under the guidance of specialists.