A method of diagnosing the malignant potential of a pancreatic cystic lesion in a subject including: detecting a glycan alteration in MUC5AC in a sample of pancreatic cystic lesion fluid from a subject, determining whether the glycan alteration is differentially present in the sample, and diagnosing the malignant potential of the pancreatic cystic lesion. A method of diagnosing the malignant potential of a pancreatic cystic lesion in a subject including: (a) detecting a glycan alteration in MUC5AC in a sample of pancreatic cystic lesion fluid from a subject, (b) detecting CA 19-9 in the sample, (c) determining whether the glycan alteration and CA 19-9 are differentially present in the sample, and (d) diagnosing the malignant potential of the pancreatic cystic lesion. Related methods of treatment and kits also are included.
