A clinicopathologic and immunohistochemical study of 22 intraductal papillary mucinous neoplasms of the pancreas, with a review of the literature

Intraductal papillary-mucinous neoplasms (IPMNs) of the pancreas are rare l esions. We undertook this study to analyze these tumors by focusing on the diagnostic criteria and correlating the histologic features with clinical p rognosis. Twenty-two cases of IPMN were retrieved from the Endocrine Tumor Registry of the Armed Forces Institute of Pathology. Blocks or unstained sl ides were available for histochemical and immunohistochemical studies (incl uding proliferative markers and cell cycle regulators) and K-ras oncogene m utations in 15 cases. Patient follow-up was obtained in all of the cases. I PMN occurs in both genders with a slight male predominance, with a mean age at presentation of 64.4 years (range, 48-85 yr). The patients presented wi th abdominal pain. The neoplasms were radiologically and grossly cystic, us ually (18 cases of 22) located in the head of the pancreas. Histologically, the tumors consisted of intraductal papillary proliferations protruding in to and expanding the pancreatic ducts. Invasion into the surrounding pancre atic parenchyma was detected in 15 cases. Chronic pancreatitis was present in all of the cases. p27 immunoreactivity always exceeded the immunoreactiv ity of cyclin E. K-ras oncogene mutations were detected in two cases. Patie nts were treated with a complete surgical resection (n = 7) or a Whipple pr ocedure (n = 13), Only 2 of 22 patients died of disease (3 died immediately postoperatively and 3 died of unrelated causes), whereas the remaining 14 patients were alive at last follow-up, without evidence of disease, an aver age of 58.2 months after initial presentation. IPMNs are rare, distinctive neoplasms, with complex intraductal papillae, that can be easily separated from in sift ductal adenocarcinoma and mucinous cystic neoplasms, The high ratio of p27 protein to cyclin E supports the excellent prognosis of these neoplasms, despite the presence of invasion and K-ras oncogene mutation.