Main duct and mixed type intraductal papillary mucinous neoplasms without enhancing mural nodules: Duct diameter of less than 10 mm and segmental dilatation of main pancreatic duct are findings support surveillance rather than immediate surgery

Abstract

ObjectiveThe guidelines for pancreatic intraductal papillary mucinous neoplasms (IPMNs) recommend surgical resection of all main-duct (MD) and mixed-type IPMNs in surgically fit patients. We conducted this study to identify the rates of high-grade dysplasia (HGD) and invasive carcinoma according to the morphological features of the main pancreatic duct (MPD) in patients with MD and mixed IPMN. MethodsWe performed a retrospective study of 259 patients with histologically proven MD and mixed-type IPMNs who underwent surgery at six academic institutions. ResultsThe rate of HGD and invasive carcinoma was 11.1% (24/216) in patients without enhancing mural nodules (MNs) and 69.8% (30/43) in patients with MNs. Multivariate analysis showed that MPD diameter of ≥10 mm [odds ratio (OR), 2.5; 95% confidence interval (CI), 1.155–5.505; P = 0.02], diffuse MPD dilatation (OR, 3.2; 95% CI, 1.152–8.998; P = 0.02), and presence of enhancing MNs in MPD (OR, 9.6; 95% CI, 3.928–23.833, P < 0.0001) were significant predictors of HGD and invasive carcinoma. Of the 216 patients without enhancing MNs, 79 patients (36.6%) having both segmental MPD dilatation and MPD diameter of <10 mm showed significantly lower rates of HGD and invasive carcinoma (3/79, 3.8%) than patients having both diffuse MPD dilatation and MPD diameter ≥10 mm (9/36, 25%, P = 0.001). ConclusionsMD and mixed-type IPMNs having segmental MPD dilatation with MPD dilation <10 mm and no enhancing MNs on imaging showed a significantly lower rate of HGD and invasive carcinoma, and watchful follow-up instead of immediate surgical resection might be possible in these patients.