a 57-year - old woman visited our hospital with right flank discomfort of two - month duration .
the serum ca 19 - 9 level was slightly elevated at 45.2 u / ml ( normal range : 0 - 37 u / ml ) . urine analysis demonstrated three to four white blood cells per high - power field , but the patient denied dysuria or other urinary symptoms .
transabdominal us showed a 67-cm , well - marginated , retroperitoneal mass with isoechogenicity relative to the liver parenchyma , and this was adjacent to the pancre atic head . while color doppler us demonstrated the hypervascularity of the tumor ( fig .
dynamic pancreas ct revealed a 7-cm , well - demarcated , low attenuating mass in the pancreatic head . on the arterial phase ct ,
this mass showed strong enhancement and also non - enhancing tubular - shaped portions ; several intratumoral vessels that were connected to the peritumoral vessels were also noted .
there was early contrast filling of the main portal vein and several prominent draining veins surrounding the mass .
on the portal venous phase ct , the mass was still well - enhancing and the extent of the non - enhancing portions within the mass was reduced compared with that seen on the arterial phase .
there was diffuse dilatation of the pancreatic duct that was most likely secondary to mass compression or invasion .
given the mass compression of the distal main portal vein , the possibility of main portal vein invasion could not be ruled out ( figs .
ercp demonstrated superior displacement of the head portion of the main pancreatic duct and diffuse mild dilatation of the main pancreatic duct ( fig .
endoscopic us showed a well - marginated , echogenic mass with several anechoic portions , and this represented cystic degeneration or hemorrhagic necrosis in the pancreas head .
it also demonstrated several large vessels within and around the mass and mild dilatation of the main pancreatic duct .
based on these imaging findings , we radiologically diagnosed the tumor as being a non - functioning islet cell tumor of the pancreatic head .
the gross specimen revealed a 6.566-cm , well - circumscribed ovoid soft - tissue mass with multifocal hemorrhagic portions and no cystic degeneration ( fig . 1f ) .
the tumor had displaced the common bile duct and the main pancreatic duct without any evidence of invasion .
microscopic examination showed a zell - ballen pattern composed of mild pleomorphic chief cells and sustentacular cells within the tumor ( fig .
immunohistochemistrical staining was positive for synaptophysin , chromogranin and s-100 protein , but negative for cytokeratin ( figs .
paragangliomas or extraadrenal pheochromocytomas are rare , affecting about one in 2,000,000 people ( 6 ) . although most paragangliomas are solitary and they arise sporadically , they can be multicentric or hereditary .
paragangliomas of the abdomen predominantly arise from paraganglia that are symmetrically distributed along the abdominal aorta in the retroperitoneum .
the most prominent collection is near the origin of the inferior mesenteric artery ( the organ of zuckerkandl ) , which is where the majority of abdominal paragangliomas originate .
other less common locations of abdominal paragangliomas include the gallbladder , urinary bladder , prostate , spermatic cord , uterus and duodenum ( 2 ) .
although paragangliomas occur in a variety of anatomic locations , they have nearly identical imaging features , namely a homogeneously or heterogeneously hyperenhancing , soft - tissue mass with cystic areas on ct scanning and multiple areas of signal void interspersed with hyperintense foci ( a salt - and - pepper appearance ) within the tumor on the mr imaging ( 2 ) .
the mean age of these eight patients was 67 years ( range : 42 to 85 years ) with a male to female ratio of 1/7 .
six of these eight tumors were located in the pancreatic head , whereas the remaining two originated from the body of the pancreas .
although the available radiologic images were limited in the previously reported cases of pancreas paraganglioma ( 3 - 5 ) , the imaging findings were generally characterized as a well - defined mass with frequent areas of hypoechogenicity on us , a well - marginated , hypervascular tumor with cystic areas of low - attenuation on contrast - enhanced ct , and tumor displacement of the main pancreatic duct on ercp .
although the present case is characterized by similar findings , it is unique because the dynamic ct demonstrated robust enhancement of the mass that was comparable to that of the greater abdominal vessels , prominent intratumoral vessels and early contrast filling of the main portal vein and draining veins from the mass during the arterial phase .
the differential diagnosis of a hypervascular pancreatic mass should include islet cell tumor ( ict ) , which can be functioning or nonfunctioning according to their clinical and laboratory manifestations ( 7 ) .
functioning icts are usually less than 3 cm in size and they are homogeneously hyperenhancing during the arterial phase of contrast - enhanced ct ( 7 ) . on the other hand , nonfunctioning icts tend to be larger than functioning icts , they have a greater predilection for cystic change or necrosis , and they are heterogeneously enhancing ( 7 ) . the radiologic differentiation of pancreas paragangliomas from nonfunctioning icts can be difficult . yet to the best of our knowledge , there is no report regarding early contrast filling of the prominent draining veins of nonfunctioning icts .
therefore , early contrast filling of the prominent draining veins of this tumor and the portal vein too may be a clue for differentiating pancreas paragangliomas from nonfunctioning icts of the pancreas . in conclusion
, we report here on a patient with a rare diagnosis of primary paraganglioma of the pancreas , and this tumor was characterized by hypervascularity with prominent intratumoral vessels and early contrast filling of the draining veins from the mass . despite its rarity
, paragangliomas should be a part of the differential diagnosis of a hypervascular pancreatic mass , and especially in the setting of early contrast filling of the prominent draining veins from the mass .
 paragangliomas rarely originate from the pancreas and they are characterized on imaging studies as well - marginated , hypervascular masses with cystic areas . 
 we herein report on a case report of pancreatic paraganglioma in a 57-year - old woman , which was confirmed on pathology . 
 color doppler ultrasonography and dynamic ct demonstrated a well - demarcated , extremely hypervascular mass with prominent intratumoral vessels and early contrast filling of the draining veins from the mass . 
 endoscopic retrograde cholangiopancreatography showed that the main pancreatic duct was displaced and mildly dilated . 
CASE REPORT
DISCUSSION