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Retroperitoneum » Pancreas
Pancreatic intra-ductal papillary mucinous tumor
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Presentation An 82 year old woman presented for abdominal ultrasound as a part of her diagnostic work-up for abdominal pain. Her complaints were of one month duration and she also experienced loss of appetite.
 
 
 
Caption: Transverse midline scan
Description: There is massive dilatation of the pancreatic duct seen throughout the entire gland. Amorphous echogenic material and solid appearing areas are also noted along the posterior part of the duct. The pancreatic parenchyma is barely visible.
 
 
 
Caption:  Sagittal scan of RUQ
Description: The dilated pancreatic duct is seen in the pancreatic head and shows a gradual tapering. Septae-like material are seen within this part of the duct as well.
 
 
 
Caption: Midline transverse scan at the epigastric level
Description: The pancreatic duct in the tail region also shows septae and some solid appearing lesions. There is echogenic material seen within the dilated duct.
 
 
 
Caption: Sagittal scan of right upper quadrant
Description: The walls of the duct are lined by the echogenic material with some speckled appearance seen in the center of the duct. Some normal pancreatic parenchyma is visualized in this image.
 
 
 
Caption: Midline transverse color Doppler scan
Description: The compressed but patent splenic vein is noted here.
 
 
 
Caption: Transverse view of the mid abdomen
Description: A moderate amount of ascitic fluid is noted in the abdomen. The tip of the paracentesis needle is seen in the fluid.
 
 
 
Caption: Midline transverse scan
Description: The dilated pancreatic duct is noted, with the septae in the duct showing contrast enhancement. There is a moderate amount of ascites and small incidental hepatic cysts are noted.
 
 
 
Caption: Midline transverse scan
Description: The dilated pancreatic duct is seen with solid components within that show enhancement.
 
 
 
Caption: Midline transverse scan
Description: The dilated pancreatic duct in the region of the head shows gradual tapering. Some solid components and debris are seen within. The duodenum is seen in very close proximity to the pancreatic head.
 
Differential Diagnosis Pancreatic intra-ductal papillary mucinous tumor, pancreatic stricture due to other causes
 
Final Diagnosis Pancreatic intra-ductal papillary mucinous tumor
 
Discussion Pancreatic intraductal papillary mucinous tumor [IPMT] is a relatively newly described entity. These are tumors with low grade malignant potential, grow very slowly and are characterized by papillary growth in the main or a branch of the pancreatic duct and copious mucin production resulting in dilatation of the pancreatic duct. The main and/ or branch of the pancreatic duct may be involved. The tumor constitutes a range of histologic appearances from an adenoma to frank malignancy. 

IPMT may be classified as branch duct type, main duct type or mixed. The former is usually benign, while main duct type and mixed type tumor may be malignant.

Imaging modalities for diagnosing IPMT: These include ultrasound in all its different forms [transabdominal ultrasound, endoscopic ultrasound, intraductal ultrasound and contrast enhanced ultrasound], CT pancreatography, MRCP and ERCP.

Ultrasound features: Transabdominal ultrasound demonstrates:
1. A massively dilated pancreatic duct which may be diffusely dilated or segmentally dilated.
2. If segmental involvement, cystic ballooning of the duct may be seen and the rest of the pancreas is normal.
3. The wall of the duct is usually thin, but if very thick walls present- that signifies malignancy.
4. Intraductal echogenic mural nodules, papillary growth or any other solid components may be seen.
5. There may be echogenic material within the duct due to the presence of mucin.
6. Associated parenchymal atrophy may be present if the ductal dilation has been long standing.
7. In advanced stages, there may be secondary blockage of the common bile duct by the tumor or inspissated mucin.
8. There may be a pancreatico-biliary or a pancreatico-duodenal fistula.

Importance of contrast enhanced ultrasound: The use of ultrasound contrast agents in IPMT is mainly to distinguish between the benign and malignant type. A quantitative difference in the enhancement intensity is a feature that is used to do so and has shown promising results.

ERCP is most often diagnostic as it demonstrates the protrusion of the papilla and jelly like mucin at the pancreatic orifice.

Overall, IPMT has a much better prognosis than adenocarcinoma, if the IPMT is of the malignant type.
 
Case References 1. Procacci C, Megibow A, Carbognin G, et al. Intraductal Papillary Mucinous Tumor of the Pancreas: A Pictorial Essay. Radiographics 1999; 19:1447-1463. http://radiographics.rsnajnls.org/cgi/content/full/19/6/1447.
2. Kloppel G, Kosmahl M, et al. Intraductal neoplasms of the pancreas: cystic and common. Pathologe. 2004 Dec 8; [Epub ahead of print].
3. Sohn TA, Yeo CJ, et al. Intraductal papillary mucinous neoplasms of the pancreas: an updated experience. Ann Surg. 2004 Jun; 239(6):788-97; discussion 797-9.
4. Tanaka M. Intraductal papillary mucinous neoplasm of the pancreas: diagnosis and treatment. Pancreas. 2004 Apr; 28(3):282-8.
5. Itoh T, Hirooka Y, et al. Usefulness of contrast-enhanced transabdominal ultrasonography in the diagnosis of intraductal papillary mucinous tumors of the pancreas. Am J Gastroenterol. 2005 Jan; 100(1):144-52.
 
Follow Up This patient had an elevated CA 19-9 levels. MRCP also demonstrated the dilated duct which tapered towards the pancreatic head and exhibited a septated/ multiloculated appearance. An ERCP was performed on this patient which was diagnostic. There was mucin seen at the pancreatic orifice and the minor papilla appeared bulging with a villous appearance. An adequate pancreatogram could not be obtained. Copious amount of inspissated mucin was extracted from the massively dilated pancreatic duct into the duodenum. A sphincterotomy was performed and a nasogastric drain was placed.
 
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