The "new kid on the block:" - Intraductal papillary mucinous neoplasms of the pancreas: Current concepts and controversies

IPMNs are now recognized as a distinct tumor type in the pancreas with specific clinicopathologic characteristics: endoscopic (mucin extrusion from Ampulla), radiologic (dilatation of the ducts, often with nodularities), pathologic (mass-forming intraductal neoplasia with mucinous cells and papillae), and indolent behavior. Correct diagnostic identification of this tumor is important because it has a significantly better overall outcome than ordinary ductal adenocarcinoma. On the other hand, the IPMN category encompasses a subset of patients that may have progression to invasive carcinoma, dissemination, and behavior of an aggressive fashion. Small IPMNs (<3 cm) that are predominantly cystic, are devoid of papilla formation and involve predominantly the branch ducts, are generally adenomas and clinically silent and therefore amenable to conservative management. Others may be unpredictable, and thus careful diagnostic work-up and thorough analysis of the tumor are warranted. A multidisciplinary approach and use of the best available diagnostic methods in expert hands may be necessary. The possibility of the field-defect phenomenon, multifocality, and unpredictability, combined with the difficulty (and current inadequacy) of the clinical follow-up of this organ have led some authors to take a more aggressive approach in the management of these cases. As the pathogenesis of, and the molecular events that lead to, IPMNs are better understood, it will become easier to determine those cases that are more prone to behave aggressively and require therapy. For cancer researchers, the IPMN category constitutes an invaluable model to study pathways of carcinogenesis.