A study by Tanno et al1 published in this issue of Gut (see page 10.1136/gut.2007.129684) shows that a branch-duct intraductal papillary mucinous neoplasms of the pancreas (BD-IPMNs) without mural nodules can be safely followed with non-operative management, confirming the results of a prospective study carried out at our institution and recently published in this journal.2

IPMNs were first described 25 years ago by Ohashi and colleagues with the name “mucin secreting cancer of the pancreas”.3 During the 1980s and early 1990s many case reports and small series of IPMNs were published but at that time IPMNs were frequently confused with other pancreatic tumours, in particular with mucinous cystic neoplasms (MCNs) of the pancreas.4 5 It was only in 1996 that the World Health Organization made a clear distinction between IPMNs and MCNs, the latter being characterised by the presence of the unique ovarian stroma with no involvement of the ductal system of the pancreatic gland.6 Mucin-producing neoplasms of the pancreas, including both IPMNs and MCNs, were considered as lesions with potential or actual malignancy, and therefore surgery was recommended for all mucinous tumours.4 5

IPMNs can affect the ductal system of the pancreas with two distinct forms: neoplasms that arise from the main duct with or without a synchronous involvement of the branch ducts (MD-IPMNs) or IPMNs involving only the secondary branches (BD-IPMNs).

The incidence of IPMNs has increased dramatically over the past 10 years and, nowadays, they represent the second indication for pancreatic resection at our institution, after ductal adenocarcinoma. This is basically related to the widespread use of cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance cholangiopancreatography (MRCP) that led to “incidental” diagnosis of cystic neoplasms of the pancreas (including IPMNs) in a large number of asymptomatic patients. …