Focus on the intraductal papillary mucinous neoplasm of the pancreas.

Intraductal papillary mucinous neoplasms (IPMNs) are rare pancreatic tumours, accounting for less of 1-2% of all neoplasms of the gland. Main characteristics of IPMNs are their favourable prognosis as these pre-malignant or frankly malignant lesions are usually slow-growing tumours and radical surgery is frequently possible. According with the localization of the lesions, three different entities are identified: the main-duct IPMN (type I), the branch-duct IPMN (type II) and the mixed type (type III, involving both the main pancreatic duct and side branches). IMPNs do not present pathognomonic signs or symptoms. Obstruction of the main pancreatic duct system may cause abdominal pain and acute pancreatitis (single or recurrent episodes). The tumour may be incidentally discovered in asymptomatic patients, particularly in those with branch-duct IPMNs. In clinical practice, any non-inflammatory cystic lesion of the pancreas should be considered as possible IPMN. Computed tomography, magnetic resonance imaging with cholangiopancreatography and endoscopic ultrasonography can localize IPMN and assess its morphology and size. The choice between non-operative and surgical management strictly depends from the risk of malignancy and of the definitively distinction between benign and malignant IPMNs. Main-duct IPMNs are at higher risk of malignant degeneration, especially in older patients; as a consequence no doubt does not exist as concerns the need of surgery for IPMN type I and III. A less aggressive surgical approach as well as the possibility of conservative management have been suggested for asymptomatic, small size (< 3-3.5 cm), branch-duct IPMN.