Review ArticleIntraductal papillary mucinous tumor of the pancreas☆
Section snippets
Nomenclature
Since the initial description of IPMT, various names have been given to this disease, some of which are still used (Table 1).Atypical papillary hyperplasia, intraductal papilloma, papillary adenoma52 Mucinous ductal ectasia6 Intraductal papillary hyperplasia104 Villous adenoma105, 106 Diffuse villous carcinoma of the duct of Wirsung, villous adenoma of the main pancreatic duct107 Intraductal cystadenoma59 Cystic adenocarcinoma108 Carcinoma in
Pathology
IPMT may involve the main pancreatic duct (main duct type [MDT-IPMT]), in either a diffuse or segmental manner, or the tumor may arise in a branch duct (branch duct type [BDT-IPMT]). The hallmarks of IPMT are diffuse or segmental ductal dilation in the absence of a stricture of the main or branch duct, intraductal growth of mucin-producing epithelial lining cells that have a “flat” or papillary-villous appearance, and protrusion and dilation of the major and/or minor papilla from which mucous
Epidemiology and etiology
Because IPMT is a relatively rare entity only recently described in detail, its epidemiology remains unclear. The true incidence of IPMT in the population is unknown, although surgical series suggest that it accounts for between 8% and 20% of pancreatic resections for malignancy.4, 18 There is a perception among gastroenterologists and surgeons that the incidence of this entity is rising. Whether this represents a true increase or reflects increased use and improved accuracy of abdominal
Pathogenesis
IPMTs are clearly premalignant lesions, with up to 50% of patients having invasive carcinoma at operation.9, 26, 27 A hyperplasia-adenoma-carcinoma sequence has been proposed for the pathogenesis of IPMT based on histopathologic and molecular biology studies.8, 28, 29, 30 The natural history of this proposed sequence is unknown, although the progression is thought to be extremely slow. A case has been reported of noninvasive adenocarcinoma in an IPMT in which the tumor was resected 27 years
Molecular pathogenesis
Despite advancing knowledge of the molecular basis of pancreatic ductal adenocarcinoma, little is known about the molecular abnormalities in the less common IPMT. Available data suggest that the evolution of neoplasia in IPMT follows molecular pathways that are similar but distinct from those of pancreatic ductal adenocarcinoma (Table 5).Empty Cell IPMT (carcinoma) Pancreatic ductal adenocarcinoma P53 overexpression 50%
Clinical features
IPMT occurs most commonly in men in the age range of 60 to 70 years. Most patients have a long history of recurrent acute pancreatitis (30%-80%) or symptoms that mimic chronic obstructive pancreatitis. Symptoms are likely caused by intermittent obstruction of the main pancreatic duct. Other symptoms include weight loss (46%), anorexia (20%), and steatorrhea (17%). Jaundice and vomiting occur in about 10% of cases. Many patients are asymptomatic and the tumor is found incidentally when an
Differential diagnosis
IPMT is often misdiagnosed initially based on clinical findings as chronic obstructive pancreatitis, MCT of the pancreas, or pancreatic ductal adenocarcinoma. Conventional imaging studies such as CT and transabdominal US often cannot distinguish these distinct clinical entities. Misdiagnosis or delay in diagnosis may result in inappropriate therapy and such errors favor the carcinomatous process.
Although the surgical pathologist can rely on the presence or absence of ovarian-type stroma to
Diagnosis
A variety of imaging methods are available for the diagnosis of IPMT, including the identification of malignant transformation. There is no “imaging method of choice” because each has advantages and disadvantages; optimally, a combination of methods will usually be required for diagnosis and preoperative assessment including staging.
Preoperative assessment of extent and invasiveness: Is it important?
Patients with an IPMT that are surgically resected have a good prognosis. Because a large proportion of IPMT do not contain foci of invasive carcinoma, and because there is evidence to suggest a long course before malignancy develops, surgery is not required for all patients, especially if imaging and other studies favor the presence of a benign tumor. Nonsurgical approaches might be used more frequently if there were reliable methods for detecting malignancy.
Smoking, excessive use of alcohol,
Main duct-type IPMT
Total resection of the tumor should be performed for MDT-IPMT tumors of any size originating in the main pancreatic duct. Local resection (i.e., pancreaticoduodenectomy, pylorus preserving pancreaticoduodenectomy, or partial pancreatectomy) is sufficient when an IPMT is localized to a segment of the pancreas. Unfortunately, when an MDT-IPMT is present in the head of the pancreas and the main duct is diffusely dilated upstream, it is impossible to differentiate diffuse invasion of the main duct
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2017, Mayo Clinic ProceedingsCitation Excerpt :Intraductal papillary mucinous neoplasms may occur at any age; however, the mean age at diagnosis is 65 years and both sexes are almost equally affected. Most patients with IPMNs are free of symptoms and diagnosed incidentally35; however, patients may present with abdominal pain, malaise, jaundice, or acute pancreatitis.36-38 Intraductal papillary mucinous neoplasms are frequently found in the head and uncinate process; however, they can occur throughout the pancreas.
Management of patients with pancreatic cystic lesions: A case-based survey
2017, PancreatologyCitation Excerpt :During the last decades, pancreatic cystic lesions (PCL) have been diagnosed with an increasing prevalence, especially in elderly asymptomatic patients, and are found in approximately 8–20% of all pancreatectomy specimens [1–3].
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Reprint requests: James J. Farrell, MD, Division of Digestive Diseases, UCLA School of Medicine, Los Angeles, CA 90095.