Calcifying obstructive pancreatitis: a study of intraductal papillary mucinous neoplasm associated with pancreatic calcification.

BACKGROUND AND AIMS: We have observed intraductal papillary mucinous neoplasm (IPMN) associated with pancreatic calcification. The aim of this study is to describe the profile of IPMN associated with calcification and gain insights into the pathogenesis of calcification in IPMN. METHODS: We identified 10 patients with IPMN with pancreatic calcification, of whom 7 underwent pancreatic resection. We reviewed demographic data, history of previous pancreatitis, and radiological and histological features of these patients. RESULTS: In patients with IPMN with calcification (mean age, 65 +/- 12 yr; 50% men), a diagnosis of chronic calcifying pancreatitis was entertained in 5 of 10 patients; 2 patients had undergone previous endoscopic therapy for stone removal. There was no previous history of pancreatitis in 9 of 10 patients. Radiologically, calcifications were seen diffusely throughout the gland in 8 of 10 patients and interpreted as chronic calcific pancreatitis. Although 1 of the 7 patients who underwent resection had diffuse IPMN throughout the gland, 6 patients had IPMN confined to the head or uncinate process (mean size, 2.75 cm; range, 1.1-5 cm). Histologically, 6 of 7 IPMNs were adenomas, and 1 patient had invasive cancer. No patient had intratumoral calcification. All 7 patients had calcification within the main pancreatic duct and/or side branches, often within inspissated mucus. CONCLUSIONS: IPMN associated with pancreatic calcification can lead to misdiagnosis and inappropriate treatment for chronic calcifying pancreatitis. In the absence of intratumoral calcification or a previous history of long-standing chronic pancreatitis, calcification in IPMN likely represents a unique and hitherto unrecognized form of calcifying obstructive pancreatitis caused by prolonged partial obstruction of the pancreatic duct.