A mass component of papillary proliferation commonly seen in IPMN of pancreas was absent and micropapillary proliferation was predominant in our case, but the histological features of cystic dilated duct with mucin hypersecreation, and moderate cellular atypia were resemble with that of IPMN of pancreas. This evidence concerns the gene MUC5AC and pancreatic intraductal papillary-mucinous neoplasm.