MUC5AC and invasive ductal breast carcinoma: Though IPMNs originate from the pancreatic duct cells similar to invasive ductal adenocarcinoma of the pancreas, IPMN exhibits a unique clinical feature different from invasive ductal adenocarcinoma, such as secretion of a large quantity of mucin by the neoplasm, and slow and expansive growth associated with low malignant potentials for metastasis and invasion compared to invasive ductal adenocarcinoma.