About 41% of cases diagnosed as MCN and IPMN by EUS in our study had a cyst fluid CEA level of less than 192 ng/mL (the recommended cutoff point of the American Gastroenterological Association), which indicates the moderate specificity of this method for differentiating mucinous cysts from non-mucinous cysts. This evidence concerns the gene CEACAM5 and pancreatic intraductal papillary-mucinous neoplasm.