Splenic involvement of an infected pseudocyst is known to be a rare complication of infected pancreatic necrosis following pancreatitis. We present herein a case of chronic alcoholic pancreatitis complicated by a major infected pseudocyst formation involving the spleen, with subsequent rupture and complete disappearance of the entire spleen. A 60-year-old Japanese man with a history of chronic alcoholic pancreatitis with a pancreatic tail pseudocyst was referred to us because of severe epigastralgia. CT revealed spontaneous rupture of the pseudocyst into the stomach and free air in the pseudocyst. The body and tail of the pancreas were disrupted due to pancreatic necrosis, and the splenic parenchyma was also partially ruptured and disrupted with large tears of the splenic surface. One month later, CT showed almost complete disruption of the splenic parenchyma. Three months later, CT showed remarkable regression of the pseudocyst and complete disappearance of the entire spleen. Although splenic involvement of pancreatic pseudocysts should be considered to be a potentially lethal complication because of hemorrhage or infection, it can possibly be treated conservatively. In the present case, complete obstruction of both the splenic artery and vein due to chronic inflammation, and spontaneous drainage into the stomach were the most probable causes for the spontaneous regression without surgical treatment. This is the first report of splenic disappearance after splenic rupture demonstrated by CT
