Features and Choice of Treatment of Acute and Chronic Pancreatic Pseudocysts - with Special Reference to Invasive Intervention

Aims: It was the aim of this study to characterize the features of acute and chronic pancreatic pseudocysts (PPs) and to identify the factors predictive of the need for invasive treatment. Methods: Thirty-six patients with PPs treated at Nippon Medical School between January 1995 and December 2004 were studied retrospectively. The cases were divided into 4 groups based on 4 features: association with acute pancreatitis, association with chronic pancreatitis, spontaneous resolution, and persistent symptoms requiring therapeutic intervention. Group 1 included 9 patients with acute PPs which resolved spontaneously. Group 2 included 9 patients with acute PPs with persistent symptoms or associated complications requiring interventional treatment. Group 3 included 9 patients with chronic PPs which resolved spontaneously, and group 4 included 9 patients with chronic PPs with persistent symptoms or associated complications requiring interventional treatment. Results: Among the 36 patients, 13 were women and 23 were men. The etiologies were pancreatitis due to alcoholism in 18 cases (50.0%), biliary tract disease in 8 cases (22.2%) and other conditions in 10 cases (27.8%). The average duration of follow-up was 24.2 ± 18.5 months. The patients in group 1 were significantly older than those in group 2 (67.6 ± 16.1 vs. 40.6 ± 14.1 years; p = 0.011). The mean size of the PPs was significantly larger in groups 1 and 4 than in group 3 (p < 0.05) and significantly larger in group 2 than in group 4 (p < 0.05). There were no significant differences between groups 1 and 2 in the size of the PPs or in the Ranson score of previous pancreatitis. The increase in size of the PPs during follow-up in each of the spontaneously resolved groups (groups 1 and 3) differed significantly from that in each of the interventional treatment groups (groups 2 and 4; p < 0.05). The main cause of the acute pancreatitis in group 1 was biliary tract disease, while that in group 2 was alcoholism (significantly different, p < 0.05). The number of patients with symptoms related to pseudocysts at the time of diagnosis was significantly higher in group 1 than in group 3. Conclusions: Growth of the PPs during follow-up is the strongest predictor of the need for invasive treatment in both acute and chronic cases. Among acute PPs, the size of the pseudocyst is not in itself a predictor of invasive treatment. Invasive treatment may pose higher risks for pseudocysts with an etiology of alcoholic acute pancreatitis. However, the size of the pseudocyst may be a more important prognostic factor than an etiology of pancreatitis.