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 < .05).
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.
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