Pathology and molecular biology of intraductal papillary mucinous neoplasms

In recent times, the reported incidence of intraductal papillary mucinous neoplasms (IPMN) has increased dramatically. There is no clear reason for this striking increase with some arguing that awareness and recognition of IPMN, improved imaging modalities and an aging population are not sufficient to account for this increase in incidence. Whatever the reason, IPMN now constitute a significant proportion of pancreatic neoplasms worldwide. Key issues in the clinical management of IPMN, including recurrent pancreatitis, the risk of invasive adenocarcinoma and ongoing research, must be underpinned by accurate and reproducible pathological assessment. IPMN are defined as grossly visible, noninvasive, mucin-producing, predominantly papillary or rarely flat epithelial neoplasms arising from the main pancreatic duct or branch ducts, with varying degrees of duct dilatation. IPMNs usually produce a lesion >1 cm in diameter and include a variety of cell types with a spectrum of cytologic and architectural atypia (1).