The molecular pathology of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas has not been well characterized, and there are no reliable markers to predict the presence of associated invasive carcinoma in patients with IPMNs. We investigated the clinicopathologic characteristics of 37 IPMNs and the immunohistochemical findings of these tumors to investigate the malignancy of IPMNs.