Classified as main duct, combined, or branch duct type
Clinical Issues
•
20-50% of resected cystic pancreatic tumors
Incidence increasing due to increased incidental detection on imaging for other reasons
•
Most patients are asymptomatic
Symptoms associated with intermittent pancreatic ductal obstruction by tenacious mucin &/or low-grade pancreatitis
•
Average age at presentation: Mid 60s
•
Prognosis better than conventional ductal adenocarcinoma
Noninvasive tumors: 5-year survival rate: > 75%
Invasive tumors: 5-year survival rate: 34-62%
–
Significantly better than pancreatic ductal adenocarcinoma
Invasive components may be very focal, requiring submission of entire lesion
•
Surgical resection treatment of choice
Vast majority surgically resectable
Macroscopic
•
Most common in pancreatic head
•
Often involve only portion of pancreatic duct but may be multifocal or involve entire duct
TERMINOLOGY
Abbreviations
•
Intraductal papillary mucinous neoplasm (IPMN)
Definitions
•
Grossly visible, mucin-producing epithelial neoplasm present within main pancreatic duct &/or its branches
•
Subclassification based on duct(s) involved
Main duct type
–
Mucinous epithelium confined to main pancreatic duct
Combined type
–
Mucinous epithelium involving both main duct and branch ducts
Branch duct type
–
Mucinous epithelium confined to branch ducts
ETIOLOGY/PATHOGENESIS
Molecular Features
•
DPC4/SMAD4 loss uncommon, in contrast to high-grade PanIN and invasive ductal adenocarcinoma
•
Overexpression of EGFR and ERBB2 common
•
KRAS mutations common except for oncocytic type
•
Loss of p16 increases with grade of dysplasia
Risk Factors
•
Family history of pancreatic ductal adenocarcinoma (associated with branch duct IPMN)
CLINICAL ISSUES
Epidemiology
•
Incidence
20-50% of resected cystic pancreatic tumors
–
Incidence increasing due to increased incidental detection on imaging for other reasons
–
Prevalence in general population estimated to be as high as 13.5% based on imaging studies
•
Age
Range: 25-94 years
•
Sex
Slightly more common in men but varies according to ethnicity
Presentation
•
Most patients asymptomatic
•
Symptomatic patients usually present with vague complaints related to duct obstruction/low-grade pancreatitis
Abdominal &/or back pain
Anorexia
Weight loss
•
Symptoms often present for months to years before diagnosis established
Endoscopic Findings
•
Mucin extravasation from patulous ampulla of Vater in ∼ 25% of cases, essentially diagnostic of intestinal-type IPMN
Treatment
•
Surgical resection is treatment of choice
80-98% of IPMNs are surgically resectable
contains nodular mucosa and abundant mucin (stained with yellow dye). The ampullary orifice is indicated 
. A dilated patulous ampulla with extruded mucin is a typical appearance of this tumor on endoscopy.
connected to the main pancreatic duct 
via a dilated branch duct 
.
and a large branch duct 
. The stroma is dense and fibrotic.
. The infiltrating neoplastic glands 
are of pancreatobiliary type.
