Clinical characteristics of intraductal papillary mucinous neoplasm manifesting as acute pancreatitis or acute recurrent pancreatitis

Background and Aim Comparatively little is known about acute pancreatitis or acute recurrent pancreatitis (AP/ARP) with intraductal papillary mucinous neoplasm of the pancreas (IPMN) as the causative lesion although there have been many reports about the malignant potential of IPMN as a premalignant lesion. Methods From 2000 to 2008, in a single tertiary referral center, out of 784 patients coded by the International Classification of Disease-10 with IPMN, 489 patients fulfilled our diagnostic criteria of IPMN. After careful exclusion of all known causes of AP/ARP, 34 patients with IPMN as the cause of AP/ARP were enrolled. Results AP/ARP caused by IPMN occurred in 34 (7%) out of 488 patients with IPMN, and the prevalence rate of AP/ARP was higher in the main-duct/combined type than in the branch-duct type (14% [16/111] vs 5% [18/378], respectively, P=0.002). The severity of pancreatitis was mild, based on the computed tomography severity index score (median 2, range 04). Histologic review of 24 patients with surgical resection revealed four adenomas (17%), 17 borderline malignancies (71%), two carcinomas in situ (8%), and one invasive carcinoma (4%). AP/ARP did not recur in any of the 24 surgically resected patients during the follow-up period (median 52 months, range 38115 months). Conclusions AP/ARP caused by IPMN was of infrequent occurrence. AP/ARP caused by IPMN occurred more frequently in the main-duct/combined type than in the branch-duct type. Most cases were mild in severity and benign in histopathology. AP/ARP can be an initial manifestation of IPMN, though uncommon, which leads to diagnosis.