Intraductal papillary mucinous neoplasms of the pancreas--a surgical disease.

Cystic pancreatic neoplasms are increasingly recognized, with intraductal papillary mucinous neoplasms of the pancreas (IPMNs) being the most frequently observed type. IPMNs are characterized by mucin production and epithelial growth within the pancreatic ducts, and are generally differentiated according to location: main pancreatic duct, its major side branches, or both (mixed type). IPMNs vary from benign to malignant and are considered precursor lesions of pancreatic adenocarcinoma. However, the exact time to neoplastic transformation and whether all IPMNs progress to malignant tumors is unclear. Surgical resection is warranted for all main-duct and mixed-type IPMNs (they harbor a high risk of malignancy of ~70%). By contrast, branch-duct IPMNs progress to cancer in only ~30% of cases. Thus, according to current guidelines (Sendai criteria), asymptomatic side-branch IPMNs <3 cm in size without suspicious radiological features (such as size progression) can be treated conservatively. Lately, even this approach has become controversial, owing to a number of Sendai-negative IPMNs showing malignant transformation. Although most IPMNs should be resected by standard oncological procedures (including lymphadenectomy), small Sendai-negative IPMNs can be treated with limited resections. This Review summarizes current knowledge of the treatment of IPMNs, with a particular focus on surgical approaches to this disease.