the incidence of chromafine tissue tumours is about 12/100 000/year in the adult population [ 1 , 2 ] .
paragangliomas represent an extra - adrenal form of the disease and account for approximately 10% of all pheochromocytomas .
about 70% of paragangliomas are intra - abdominal , with various localizations being described , mostly adjacent to main vessels or retroperitoneal organs [ 3 , 4 ] .
extra - adrenal pancreatic paragangliomas are exceptionally rare . there have been only 15 cases published up to 2011 . because paragangliomas have notoriously unpredictable behaviour and often metastasize late , surgical resection is a treatment of choice .
critical appreciation of vascular anatomy may define operability , enable planning a surgical strategy and may prove extremely useful during the resection . in case of an inoperable tumour with malignant behaviour , chemotherapy or therapy with radionucleotides may be used [ 6 , 7 ] .
a 53-year - old , obese ( body mass index 30.9 kg m ) , caucasian woman was referred to our department with non - specific abdominal discomfort as the only presenting symptom .
a large hypervascularized mass in the area of the pancreatic head was shown on abdominal ultrasonography and computed tomography ( ct ) .
pre - operative imaging revealed an extremely hypervacularized tumour with abundant collateral vessels from the superior mesenteric artery ( sma ) , replaced right hepatic artery ( ha ) , gastroduodenal artery ( gda ) and right renal artery ( rra ) , with an early venous filling of the dilated superior mesenteric vein ( smv ) and portal vein ( pv ) ( fig . 
the replaced right ha arising from sma was crossing in between the dilated pv and overfilled tumour - draining veins ( fig . 
extreme dilation of smv and pv in both extra- and intra - hepatic course could be expected as numerous av shunts within the tumour were present , but surprisingly , only a non - dilated , gracile splenic vein was found and no spleen enlargement was present ( fig . 
1c ) . for better evaluation of vascular anatomy , selective digital substraction angiography ( dsa )
the upper portion of the tumour received main inflow via gda and replaced right ha , the lower part via several branches of sma ( fig . 
( a ) hypervascularized tumour with early venous filling in the arterial phase of ct .
( b ) variant subtle right hepatic artery originating from sma , passing between the dilated pv and draining veins of a paraganglioma .
( c ) isolated dilation of the pv with surprisingly gracile splenic vein without any spleen enlargement . 

figure  2:(a and b ) ct volume rendering images with dilated pv and an early contrast filling of dilated peritumoral veins . 

( e ) complementary tumour blood supply via capsular branch of rra draining into the portal system .
( f ) pv dilation in the venous phase of angiography . cross - sectional ct imaging .
( a ) hypervascularized tumour with early venous filling in the arterial phase of ct .
( b ) variant subtle right hepatic artery originating from sma , passing between the dilated pv and draining veins of a paraganglioma .
( c ) isolated dilation of the pv with surprisingly gracile splenic vein without any spleen enlargement .
( a and b ) ct volume rendering images with dilated pv and an early contrast filling of dilated peritumoral veins .
( e ) complementary tumour blood supply via capsular branch of rra draining into the portal system .
( f ) pv dilation in the venous phase of angiography . during the laparotomy a tumour with numerous , large pulsating veins running on its surface was found .
after partial mobilization was completed , all main inflow and outflow vessels were secured prior to pancreaticoduodenectomy .
after division of gda and capsular branch of rra , the tumour diminished to about one half of the original size .
the neck of the pancreas was divided and dilated arterial and venous branches towards the tumour isolated . the major problem during this step turned out to be severe venous congestion caused by local av shunts .
the draining venous branches had to be divided first to gain access to hypertrophied feeding arteries at the very end of the dissection .
we considered dissection too lengthy to clamp the main arterial stems ( sma and celiac trunk ) for a prolonged period of time , and so a blood loss of 2000 ml during almost 9 h of surgery was tolerated .
histopathologically , the tumour characteristics typical of paraganglioma were present with chromogranin , synaptophysin , neuron - specific enolase and s-100 protein positivity in the immunohistochemical assay ( fig . 
the tumour had a strong fibrous capsule , no invasion to neighbouring tissue , lymphatic or blood vessels was found .
the only abnormality in a post - operative period was an unexpected transient hepatal panel elevation with a peak on post - operative day 7 ( fig . 
although no invasive haemodynamic measurements were performed neither pre - operatively nor in the post - operative period , we speculate that this could have been an effect of changed liver inflow haemodynamics after the tumour excision .
extreme pre - operative smv and pv dilation without splenic vein dilation in the presence of av shunts could be a result of  a high flow 
pre - operatively , the large proportion of the arterial inflow consisted of arterial blood shunting directly into the pv from tumour feeding arteries .
as both the left and the right ha were subtle , they provided for only non - substantial oxygen - rich hepatic inflow .
thus , tumour removal could lead to a critical decrease of oxygen delivery to the liver .
the patient is now 49 months after pylorus preserving pancreaticoduodenectomy , the regular follow - up with positron emission tomography - computed tomography ( pet / ct ) has been performed and no recurrence has been observed so far . 

a large tumour may require an extensive surgical approach , careful dissection and en bloc resection irrespective of whether it actually represents intraparenchymatous or only a perivascular ,  organ adjacent paraganglioma .
special attention shoud be paid to the possibility of av shunting within a tumour , either for the unestimated risk of a paradoxical embolism into the portal system ( when attempting pre - operative embolization ) , or for possible intra - operative technical problems ( bleeding caused by venous congestion or while manipulating the tumour ) .
low resistance hepatic inflow in the presence of significant av shunts within the tumour in this localization may result in a significant change of hepatic perfusion after tumour removal . even though this is the first report to describe such changes and no invasive haemodynamic measurements
this research received no specific grant from any funding agency in the public , commercial or not - for - profit sectors .
 pancreatic paragangliomas are extremely rare with less than 20 cases ever described in the world literature . 
 there is no detailed report of the vascular anatomy in this entity and its possible impact on patient management . 
 we present a case of large pancreatic head paraganlioma in a 53-year - old woman . 
 the tumour had a predominant arterial blood supply via both the hepatic artery and the superior mesenteric artery . 
 complex inflow was complemented by supplementary branches from the right renal artery . 
 the arteriovenous communications within the lesion represented the most dangerous aspect of excision and the tumour removal was accompanied with a considerable blood loss . 
 after pancreaticoduodenectomy , patient experienced transient elevation of liver function tests with no other identifiable cause than a change in portal haemodynamics . 
 it is advisable that the precise knowledge of vascular anatomy in pancreatic head paraganglioma should be obtained prior to any intervention . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONFLICT OF INTEREST