Intraductal Papillary Mucinous Neoplasm



Intraductal Papillary Mucinous Neoplasm


Mari Mino-Kenudson, MD









In IPMN, main-duct type, the markedly dilated main duct image shows nodular mucosa with abundant mucin (stained with yellow dye). The ampullary orifice is indicated image.






IPMN, branch-duct type, features a small cyst with a smooth lining image connected to the main pancreatic duct image through a dilated branch duct image.


TERMINOLOGY


Abbreviations



  • Intraductal papillary mucinous neoplasm (IPMN)


Definitions



  • Grossly visible, mucin-producing epithelial neoplasm that primarily grows within main duct &/or its branches


  • Subclassification based on type of duct involvement



    • 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


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Most common cystic tumor of pancreas



      • Approximately 8-20% of all resected pancreatectomy specimens


  • Age



    • Range: 25-94 years



      • Average: 63 years


  • Gender



    • Slightly more common in men


Presentation



  • Symptoms associated with intermittent pancreatic ductal obstruction



    • Abdominal pain


    • Back pain


    • Anorexia


    • Weight loss


    • Recurrent episodes of pancreatitis


  • Symptoms often present for months to years before diagnosis is established


  • Growing number of cases discovered incidentally during imaging for another indication


Endoscopic Findings



  • Mucin extravasation from patulous ampulla of Vater


Treatment



  • Surgical resection is treatment of choice



    • 80-98% of IPMNs are surgically resectable


Prognosis



  • Noninvasive tumors: 5-year survival rate > 75%


  • Invasive tumors: 5-year survival rate is significantly lower (34-62%) than for noninvasive tumors



    • Still significantly better than that of conventional pancreatic ductal adenocarcinoma


IMAGE FINDINGS


CT Findings



  • Main-duct or combined type



    • Markedly dilated main duct often associated with dilated large branch ducts


  • Branch-duct type



    • Single or numerous cysts that represent dilated branch ducts


ERCP Findings



  • Dilated main pancreatic duct &/or branch ducts in absence of stricture


  • Filling defects due to papillary projections of neoplasm &/or mucous plugs


MRCP Findings



  • In addition to dilated ducts, mural nodules are better visualized



    • Indicative of higher grade lesion



MACROSCOPIC FEATURES


General Features



  • Most common in pancreatic head



    • Often involve only a portion of pancreatic duct


    • Some are multifocal


    • Entire gland may be involved


  • Main-duct and combined types



    • Florid papillary projections, often in background of dilated ducts


  • Branch-duct type



    • Single or multiple peripheral cysts that connect to main duct, often with smooth lining


  • Mural nodules &/or solid components may be seen in IPMNs with invasion

Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Intraductal Papillary Mucinous Neoplasm
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