Number of Worrisome Features Is Associated with Increasing Risk of Malignancy in Intraductal Papillary Mucinous Neoplasm (IPMN)

Abstract

Background: The 2017 revised IAP guidelines for management of IPMN describe worrisome features (WF) and high-risk stigmata (HRS), recommending resection in the latter and further workup and close surveillance for patients with WF. The effect of multiple WF on the likelihood of malignancy has not been evaluated. Methods: 810 patients who underwent pancreatic resection for IPMN in two tertiary referral centers were identified from prospective institutional databases. Patients were retrospectively categorized into subgroups according to the number of WF or HRS, and presence of malignancy, defined as high-grade dysplasia (HGD) or invasive cancer on final pathology. Results: 379 (47%) patients had HRS, 370 (46%) had one or more WF, and 61 patients (7%) had neither. Malignancy was present in 70% (n=267) of patients with HRS and in 30% (n=127) of those with WF. Only 3/61 patients without WF/HRS had malignancy, and all only in the form of HGD. The risk of malignancy increased in a stepwise fashion with the number of WF, was 22%, 34%, and 59%, with 1, 2, and 3 WF, respectively (p= 0.001), and reached 100% in patients with 4 or more. Although the relative risks differed for particular WF, the AUCs were not statistically different. Conclusion: We confirm that presence of HRS in IPMN is associated with a very high likelihood of malignancy. The presence of a single WF has a malignancy risk of 22%, and additional WF increase this risk significantly. When 3 or more are present, the risk is similar to that of HRS.