Factors in intraductal papillary mucinous neoplasms of the pancreas predictive of lymph node metastasis

Background: Little is known about the frequency of lymph node metastasis (LNM) in intraductal papillary mucinous neoplasms (IPMNs), and we have not been able to determine how much lymph node dissection is necessary in individual cases. The aim of this study was to investigate the predictive factors for the LNM in IPMNs. Methods: Medical records of 120 patients pathologically diagnosed as having IPMN were reviewed, and 16 possible predictive factors regarding the LNM were analyzed. Results: LNM was observed in 7 patients (6%), all of whom were diagnosed as having mural nodules preoperatively. Sensitivity, specificity, and accuracy of preoperative imaging for detecting mural nodules of IPMNs in this study were 84, 97, and 90%, respectively. Univariate analysis using 61 patients having mural nodules preoperatively revealed that the size of mural nodules ≥10 mm and positive imaging findings for invasive tumor and possible LNM were significant predictive factors for the LNM. Multivariate analysis demonstrated that only an imaging finding for invasive tumor was an independent significant predictive factor. Positive and negative predictive values of the imaging finding of invasive IPMNs for LNM were 50 and 98%, respectively. Conclusions: Standard lymph node dissection would be recommended in patients with IPMNs with mural nodules demonstrating preoperative imaging findings for invasive carcinomas.