Transverse colon displacement is a manifestation of pancreatic cysts. Pseudocysts in the head of the pancreas can widen the duodenal flexure and displace the transverse colon upward or downward. The pancreaticcyst includes true cysts, pseudocysts and cystic tumors. In addition to the exclusion of gastrointestinal cavity lesions, compression and displacement of the cyst on the surrounding organs can also be seen. If a large pseudocyst is present behind the stomach, barium can show that the stomach is pushed forward and the lesser curvature of the stomach can be compressed. So, what are the causes of transverse colon displacement? The following are the causes of transverse colon displacement: pancreatic pseudocysts are cysts formed when overflowing blood and pancreatic fluid enters the peripancreatic tissue or, in rare cases, enters the small omental sac and wraps around it. The difference between a pseudocyst and a true cyst is that the latter occurs in the pancreatic tissue, the cyst is inside the pancreas, and the inner layer of the cyst is composed of glandular ducts or alveolar epithelial cells; whereas the former is a cyst formed by the peri-pancreatic tissue that encapsulates the fluid, and there are no epithelial cells inside the cyst wall, so it is called a pseudocyst. About 75% of pseudocyst cases are caused by acute pancreatitis, about 20% of cases occur after pancreatic trauma, and 5% of cases are caused by pancreatic cancer. A group reported 32 cases of pseudocysts, 20 of which occurred after acute pancreatitis, 3 after abdominal trauma, another 8 without a clear etiology, and another 1 due to compression of pancreatic fibrosarcoma. Among the 20 cases that occurred after acute pancreatitis, the earliest cyst appeared was one week after the onset of the disease, the latest was 2 years after the onset of the disease, and most were during 3 to 4 weeks after the onset of the disease. Pancreatic fluid containing a variety of digestive enzymes exudes from the necrotic pancreatic tissue into the retroperitoneal space around the pancreas, causing an inflammatory reaction and fibrin deposition, which forms a fibrous envelope after a week to several weeks, and the retroperitoneum forms the anterior wall of the cyst. Alternatively, pancreatic fluid may leak directly into the small omental sac, and the Winslow’s pore is often closed due to inflammation, and the cyst forms within the small omentum. Sometimes pancreatic fluid enters other sites along the tissue interstices to form cysts in specific sites, such as pseudopancreatic cysts in the mediastinum, in the spleen, in the kidney and in the groin.