Pancreatic pseudocysts in the 21st century. Part II: natural history.

The widespread application of ultrasonography and CT has advanced our knowledge of the natural history of pancreatic pseudocysts. It is generally agreed that acute and chronic pseudocysts have a different natural history, although many reports do not differentiate between pseudocysts which complicate acute pancreatitis and those which complicate chronic disease [1]. This makes evaluation of different treatment options difficult or impossible. Also, the treatment evaluation is complicated due to the tendency towards spontaneous resolution of the pseudocysts. The quality of data about spontaneous resolution of acute pseudocysts varies from study to study and, when there is no precise definition of the pseudocyst and when alcohol is the major cause, selection bias can occur which threatens the reliability of the results. Nevertheless, the results from published studies allow us to draw some limited conclusions and to raise questions which require further investigation.