Imaging patterns of intraductal papillary mucinous neoplasms of the pancreas: An illustrated discussion of the International Consensus Guidelines for the Management of IPMN

Abstract

Intraductal papillary mucinous neoplasms (IPMN) are being diagnosed with increasing frequency, necessitating an algorithm to help stratify patients into low- and high-risk groups, for follow-up versus more invasive evaluation. New evidence concerning their natural history and overall risk of malignancy has emerged since the 2006 International Association of Pancreatology consensus guidelines, prompting an update in 2012, that distinguishes radiologic 'worrisome features' from 'high-risk stigmata'. The aim of this article is to illustrate, with case examples, the variable imaging patterns of IPMN and how their radiologic features, such as cyst size and mural nodules, are interpreted in the context of the new 2012 guidelines. The 2012 and 2006 guidelines will be compared and discussed with reference to additional studies that have since been published. Despite these guidelines, lingering uncertainty remains about the natural history of IPMN, a source of unease to both radiologists and referring clinicians alike, mandating further refinement of clinical and radiologic parameters predictive of malignancy. Emerging data regarding the risk of extrapancreatic malignancy, as well as synchronous or metachronous pancreatic ductal adenocarcinoma remote in location from a branch duct IPMN are also reviewed. With the expanding research and evolving understanding of this clinicopathologic entity across the globe, radiologists will continue to play an important role in the management of patients with IPMN.

Radiological Workup of Cystic Neoplasms of the Pancreas

“…Establishing this connection is an important feature in the diagnosis of IPMN because this is rare in other neoplastic cystic lesions (MCN and serous cystadenoma) [11,39]. MRI and particularly using heavily T2-weighted sequences or MRCP is superior compared with CT in showing the connection of a cyst to the pancreatic duct non-invasively and in characterizing the IPMN type.…”

“…6). In 5-10% of cases, IPMNs involve the entire pancreas [6,39]. Importantly, on imaging, the tumor itself is hardly visible, but the diagnosis of IPMN can be ascertained by the sequelae of excessive mucin production.…”

“…7) [39]. The morphology of branch-duct IPMN varies with the number of affected side branches that become dilated by the production of large amounts of mucin.…”

“…The mucinous transformation of pancreatic ductal epithelium causes excessive viscous mucin production leading to obstructive dilation of the main duct or its side branches. Accordingly, IPMNs are classified according to the duct of origin: branch-duct IPMN, main-duct IPMN (focal or diffuse), or a combination of both [37,38,39]. IPMNs may be solitary or multiple and arise most commonly in the uncinate process (about 70%), but may occur in any part of the pancreas [37,38].…”

The Pathogenesis, Diagnosis, and Management of Pancreatic Cancer

“…ERCP demonstrates a dilated pancreatic duct, and filling defects, caused by intraluminal mucous plugs or papillary projections of the neoplasm itself. Magnetic resonance cholangiopancreatography (MRCP) may demonstrate ductal dilatation and mural nodules [48]. The international guidelines for management of IPMNs suggest that patients should be optimally managed with surgical resection [49].…”