IPMN of the pancreas is a fascinating entity recently drawing increasing attention. The international consensus guidelines have been revised this year (Tanaka M, et al. Pancreatology 2012;12: 183-197). My presentation summarizes the points of revision of the new guidelines.

#1. Regarding classification of IPMNs, the mixed-type category of IPMN has been preserved for the moment. The threshold of ductal dilation has been lowered to >5mm to increase the sensitivity of the diagnosis of main duct (MD-) IPMN. Considering the pre- or nonoperative management of IPMNs, the classification should be defined radiologically.   

#2. Preoperative distinction of branch duct (BD-) IPMNs from non-mucinous cysts is important to identify potentially malignant lesions and effectively guide management strategies. Cyst fluid analysis obtained by endosonography (EUS)-guided fine needle aspiration may help but is still in an investigational phase. The utility and safety remain to be determined.

#3. With regard to diagnosis of malignancy in BD-IPMNs, criteria for identifying malignancy have been revised. “Malignant stigmata” have been defined to include jaundice, contrast-enhanced solid components, MD size >10 mm. The presence of solid components or mural nodules is the most reliable predictor but the size of BD-IPMN has been moved to “worrisome features” including the size > 30 mm, thickened and enhanced cyst wall, MD size 5-9 mm, mural nodules without enhancement, MD stricture with upstream dilation, and lymphadenopathy. All BD-IPMNs with ”worrisome features” should be further evaluated by EUS.

#4. All BD-IPMNs may need periodical surveillance at least twice a year by either EUS, CT, or MR to check their malignant transformation and development of distinct ductal adenocarcinoma during observation and even after resection of BD-IPMN with surgical indication. The best modality and interval for surveillance remain to be determined. The present guidelines highlight issues that remain controversial and areas where further research is required.