Mucinous Cystic Pancreatic Tumor



Mucinous Cystic Pancreatic Tumor


Brooke R. Jeffrey, MD

Michael P. Federle, MD, FACR





Key Facts


Terminology



  • Thick-walled, uni-/multilocular, low-grade malignant tumor composed of large, mucin-containing cysts


Imaging



  • Enhancing multiseptated mass in body or tail of pancreas


  • Enhancement of thin internal septa and cyst wall ± calcification


  • MRCP: Depicts displacement, narrowing, and prestenotic dilatation of pancreatic duct


Top Differential Diagnoses



  • Pancreatic pseudocyst


  • Pancreatic serous cystadenoma


  • Pancreatic IPMN


  • Cystic islet cell tumor


  • Pancreatic epithelial (true) cyst


  • Variant of ductal adenocarcinoma


  • Lymphangioma (mesenteric cyst)


Pathology



  • Considered pre- or frankly malignant


Clinical Issues



  • Asymptomatic, epigastric pain, palpable mass


  • Diagnosis: Endoscopic ultrasound with cyst aspiration/cytology



    • Surgical resection


Diagnostic Checklist



  • Multiloculated cystic mass with enhancing septa in pancreatic body or tail



    • Usually requires resection; may not warrant additional imaging







(Left) Graphic of a mucinous cystic tumor shows a multiseptate, mucin-filled, cystic mass in the pancreatic tail that displaces the pancreatic duct. (Right) Axial MIBG in a 40-year-old woman with vague abdominal discomfort shows a mucinous cystic tumor in the pancreatic tail with multiple enhancing septa and displacement of the pancreatic duct.






(Left) Axial CECT in a 50-year-old man with vague abdominal pain shows a large complex cystic mass image in the body/tail segment of the pancreas. Note the septa and the large cystic spaces within the mass. (Right) Gross pathology from the same case shows that the resected mass image was full of mucinous fluid and had thickened septa. Histologic exam showed cellular atypia, and the lesion was considered a low-grade malignancy.



TERMINOLOGY


Synonyms



  • Mucinous macrocystic neoplasm, macrocystic adenoma, mucinous cystadenoma or cystadenocarcinoma


Definitions



  • Thick-walled, uni-/multilocular, low-grade malignant tumor composed of large, mucin-containing cysts


IMAGING


General Features



  • Best diagnostic clue



    • Enhancing multiseptated mass in body or tail of pancreas


  • Location



    • Tail of pancreas (more common)


  • Size



    • 2-12 cm in diameter


  • Morphology



    • Classified under pancreatic mucinous tumors along with intraductal papillary mucinous neoplasm (IPMN) of pancreas


    • Mucin-producing tumors must be considered when cystic lesions of pancreas are found


    • Considered premalignant or frankly malignant


Radiographic Findings



  • ERCP



    • Displacement and narrowing of main pancreatic duct adjacent to tumor


CT Findings



  • NECT



    • Hypodense unilocular or multilocular cyst


    • Focal calcifications may be seen (16% of cases)



      • Location: Wall, septum, or periphery


  • CECT



    • Multilocular cystic lesion



      • Enhancement of thin internal septa and cyst wall ± calcification


    • Unilocular cystic lesion



      • Enhancement of cyst wall


MR Findings



  • T1WI



    • Variable signal intensity based on cyst content



      • Fluid-like material: Hypointense


      • Proteinaceous or hemorrhagic: Hyperintense


    • Focal calcifications: Hypointense


  • T2WI



    • Cysts: Hyperintense


    • Internal septations: Hypointense


    • Focal calcifications: Hypointense


  • T1WI C+



    • Fat-suppression sequence



      • Enhancement of septations and cyst wall


  • MRCP



    • Depicts displacement, narrowing, and prestenotic dilatation of pancreatic duct


Ultrasonographic Findings



  • Grayscale ultrasound



    • Multiloculated cystic mass with echogenic internal septa


    • Less common: Unilocular anechoic mass


Imaging Recommendations



  • CECT or MR ± MRCP


DIFFERENTIAL DIAGNOSIS


Pancreatic Pseudocyst



  • Inflammatory changes in peripancreatic fat


  • Pancreatic calcifications and temporal evolution of lesion


  • Communicates with pancreatic duct (70% of cases)


  • Clinical history of pancreatitis or alcoholism


  • Lab data: Increased amylase (in cyst and serum)


  • Simulates unilocular mucinous cystic tumor


Pancreatic Serous Cystadenoma



  • Large, well-defined, encapsulated, sponge-like mass in pancreatic head


  • Innumerable small cysts separated by thin septa


  • Central scar with calcification



    • Calcification more common in serous than mucinous pancreatic neoplasms (38% vs. 16%)


  • Macrocystic variant of serous cystadenoma



    • Difficult to distinguish from mucinous tumor


    • Serous lesion usually has thinner wall


Pancreatic IPMN



  • Low-grade malignancy arises from



    • Main pancreatic duct (MPD)


    • Branch pancreatic duct (BPD)


    • Combined MPD and BPD


  • BPD or combined IPMN types may simulate mucinous cystic neoplasm due to presence of dilated cystic branch ducts in pancreatic tail


Cystic Islet Cell Tumor



  • Usually non-insulin-producing and nonfunctioning


  • Tumor: Cystic on NECT



    • Cyst wall shows enhancement; nonenhancing cyst contents


  • No pancreatic ductal dilatation


  • Angiography: Hypervascular primary and secondary


Pancreatic Epithelial (True) Cyst



  • Examples: von Hippel-Lindau disease and autosomal dominant polycystic kidney disease (ADPKD)


  • Rare; usually small and multiple nonenhancing cysts


  • No pancreatic ductal dilatation


Variant of Ductal Adenocarcinoma



  • Mucinous colloid adenocarcinoma or mucin-hypersecreting cancer


  • Pancreatic ductal obstruction and dilatation


  • Local invasion and regional metastases


Lymphangioma (Mesenteric Cyst)



  • Often extends from or into retroperitoneal soft tissues


  • Water density; imperceptible wall; thin septa



PATHOLOGY


General Features

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Sep 20, 2016 | Posted by in GENERAL RADIOLOGY | Comments Off on Mucinous Cystic Pancreatic Tumor

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