From a pragmatic standpoint, therefore, it may be more useful to develop guidelines that can be applied to an undetermined cystic lesion that does not fit the clinical or morphologic criteria for a pseudocyst. Some are easy: if the cyst is producing symptoms (pain, jaundice, and pancreatitis) or is bulky and demonstrably growing over time, it probably should be resected. If the main pancreatic duct is dilated, main-duct IPMN, with its 60% likelihood of containing at least in situ cancer, must be considered and resected. If there is a mural nodule or solid component, the risk of malignancy is too great to ignore. The Sendai consensus,15 which provides reliable guidelines that have been repeatedly validated, adds the element of cyst size. While there are uncommon exceptions, generally there is minimal risk of malignancy, even carcinoma-in-situ, in mucinous cysts (MCN or branch-duct IPMN) smaller than 3 cm. Consequently smaller, asymptomatic cysts without mural nodules or other solid components can be watched for growth or change, preferably by MRI/magnetic resonance cholangiopancreatography (MRCP), perhaps every year or two. Most will turn out to be branch-duct IPMNs, at least 30% of which will be multiple. Those individual cysts that fit a guideline for potential malignancy need segmental resection—metachronous small cysts can be left behind and watched for future growth and change.