Risk of misdiagnosis and overtreatment in patients with main pancreatic duct dilatation and suspected combined/main-duct intraductal papillary mucinous neoplasms

Background Segmental/diffuse dilatation of the main pancreatic duct (MPD) is the typical feature of combined/main-duct intraductal papillary mucinous neoplasms (CMD-IPMNs). MPD dilation in IPMNs may be also expression of mucus hypersecretion/obstructive chronic pancreatitis (OCP). The aim of this study was to evaluate the presence and extension of MPD involvement by tumor/OCP and assess the risk of overtreatment. Methods Retrospective analysis of suspected CMD-IPMNs resected between January 2009 and October 2014 were included. Pathologic correlations among MPD dilatation, IPMN, and OCP was searched. Results Overall, 93 patients were resected for suspected CMD-IPMNs. At pathology, CMD-IPMNs were found in 69 patients (74%). Branch-duct IPMNs (BD-IPMNs) were found in 8 cases (9%), pancreatic ductal adenocarcinoma (PDAC) in absence of IPMN in 9 (10%), cystic neuroendocrine tumor (NET G2) in 1 (1%), serous cystadenoma in 2 (2%), and OCP alone/mucinous metaplasia in 4 patients (4%). Overall, 18 patients (19%) underwent an overtreatment because unnecessary (2 BD-IPMNs, 2 serous cystadenomas, and 4 OCPs only) or too extensive resections (9 CMD-IPMNs and 1 PDAC with associated OCP). In these, total pancreatectomy was the most common procedure (67%). Median size of MPD in IPMN-involved area was 12 mm compared with 7 mm when only OCP was found ( P Conclusion There is a considerable risk of overtreatment in patients with a preoperative morphologic diagnosis of CMD-IPMNs. Partial pancreatectomy with margin examination should be performed instead of upfront total pancreatectomy. Radiologic observation can be considered in asymptomatic patients with “worrisome” MPD dilatation (5–9 mm) and lacking other high-risk stigmata.