Pancreas Divisum

Published on 19/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 Head and uncinate process of pancreas drained by ventral pancreatic duct of Wirsung via major papilla

image Body and tail of pancreas drained by dorsal pancreatic duct of Santorini via minor papilla
• MRCP: Best noninvasive modality for delineating divisum

image Dominant dorsal duct, which appears long and narrow, directly entering minor papilla

– Main pancreatic duct may be mildly dilated
image Ventral duct appears short and drains into major papilla
image No communication between dorsal and ventral ducts
image Secretin-enhanced MR/MRCP may help better delineate divisum by distending pancreatic duct
• ERCP: Most accurate method of diagnosing divisum

image Cannulation of major papilla reveals opacification of short, tapered, ventral pancreatic (Wirsung) duct

– Contrast does not flow past pancreatic head
image Cannulation of minor papilla reveals opacification of long (and sometimes dilated) dorsal pancreatic (Santorini) duct which drains nearly entire pancreas
image No communication between dorsal and ventral ducts
• CT: May demonstrate abnormally large pancreatic head or 2 distinct pancreatic moieties separated by fat cleft

CLINICAL ISSUES

• Most common congenital anatomic variant of pancreas
• May be associated with recurrent pancreatitis (mostly in children), although less than 5% are symptomatic

image Poor drainage from body and tail (due to relative stenosis at minor papilla) leads to pancreatitis
• Incidental finding in asymptomatic patient: No treatment
• Severely symptomatic patients: Surgical sphincteroplasty or endoscopic papillotomy of minor papilla
image
(Left) Graphic shows several common variations in the arrangement of the main pancreatic duct image, the accessory duct of Santorini image, and the duct of Wirsung image. The lower right image shows pancreas divisum.

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(Right) ERCP image after cannulation of the major papilla demonstrates filling of only a short ventral duct and its side branches. There is no communication with the dorsal duct, compatible with pancreatic divisum.
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(Left) ERCP in a patient with pancreas divisum and chronic pancreatitis shows dilatation and irregularity of the dorsal pancreatic duct and small pseudocysts image following cannulation of the minor papilla.

image
(Right) Coronal MRCP shows the dorsal pancreatic duct crossing the common bile duct to drain into the expected location of the minor papilla image. The ventral duct is not seen. Note the dilatation of multiple tiny pancreatic duct sidebranches throughout the gland, likely reflecting the patient’s history of chronic pancreatitis.

TERMINOLOGY

Definitions

• Anatomic variant of pancreatic ductal anatomy resulting from failure of ventral and dorsal pancreatic buds to fuse

IMAGING

General Features

• Best diagnostic clue

image Normal branching pattern of short ventral duct with no communication between ventral duct and long dorsal duct on ERCP
• Morphology

image Most common congenital anatomic variant of pancreas
image Most common variant of pancreatic ductal fusion and drainage anomalies
• Normal PD anatomy

image Head and uncinate process of pancreas drained by ventral pancreatic duct (PD) of Wirsung via major papilla
image Body and tail of pancreas drained by dorsal PD of Santorini via minor papilla

MR Findings

• MRCP is best noninvasive modality for delineating course and drainage pattern of dorsal and ventral PDs

image No communication between dorsal and ventral ducts in pancreatic divisum

– Dominant dorsal duct, which appears long and narrow, directly enters minor papilla

image Majority of pancreas is thus drained into minor papilla via duct of Santorini
image Dorsal duct may have constant, mildly dilated caliber (rather than normal tapering towards tail)
image Focal cystic dilatation of duct of Santorini is termed “santorinocele” and easily visible on MRCP
image Anatomic relationship between dorsal duct and common bile duct on MRCP MIP reconstruction results in characteristic crossing ducts sign
– Ventral duct appears short and drains into major papilla, with no connection with dorsal duct

image Posterior pancreatic head and uncinate drain into major papilla via duct of Wirsung
image Main PD may be dilated due to stenosis at minor papilla or repeated bouts of pancreatitis
• Pancreas may demonstrate abnormally high signal on T2WI and low signal on T1WI with peripancreatic free fluid in setting of superimposed pancreatitis
• Secretin-enhanced MRCP may help better delineate divisum by distending PD

image Secretin (0.2 μg/kg) induces secretion of bicarbonate-rich fluid from pancreas and increases tone of sphincter of Oddi, thereby distending PD and improving visualization
image Secretin-enhanced MR shown to have superior sensitivity/specificity for divisum compared to MR without secretin

CT Findings

• CT had sensitivity/specificity for divisum > 90% in 1 study, but MR is still considered superior
• Delineating pancreatic ductal anatomy is more difficult on CT (compared to MR), but may be aided by multiplanar and minimum intensity projection reconstructions with thin-collimation sections

image Dorsal duct, which may be dilated, can be directly traced from pancreatic tail into minor papilla
image Ventral duct is smaller (may be difficult to visualize on CT) and drains into major papilla
image No communication between ventral and dorsal ducts
• Changes in pancreatic morphology may also suggest divisum, but frequency of findings is low

image Abnormal contour of pancreatic head and neck with large pancreatic head
image 2 distinct pancreatic moieties separated by fat cleft
• Acute or chronic pancreatitis may be present

image Enlargement of gland, fat stranding, intra-/peripancreatic cysts, glandular atrophy, parenchymal or ductal calcifications, peripancreatic fat stranding, fluid collections, etc.

Radiographic Findings

• ERCP: Most accurate method of diagnosing divisum, but carries risks of invasive procedure

image Cannulation of major papilla reveals opacification of short, tapered, ventral pancreatic duct

– Contrast injected into major papilla does not flow past pancreatic head
– Guidewire inserted into major papilla does not extend past pancreatic head
– Ventral duct maintains normal branching pattern, unlike truncated, abrupt cut-off of ventral duct in pancreatic cancer
image Cannulation of minor or accessory papilla reveals opacification of long (and sometimes dilated) dorsal pancreatic duct that drains nearly entire pancreas except posterior head and uncinate

– Cannulation of minor papilla may be technically difficult due to small size
image No communication between dorsal (long) and ventral (short) PDs

Ultrasonographic Findings

• Primary limitation is inability to visualize portions of pancreas due to overlying bowel gas
• Secretin test can be performed to identify patients who will benefit from surgical sphincterotomy

image Involves sequential US measurements of PD size after secretin administration

– Secretin increases bicarbonate secretion, which overloads functionally inadequate papilla
– Secretin-induced ductal dilatation occurs in 72% of symptomatic patients due to stenotic minor or accessory papilla in pancreas divisum anomaly
image Normal result: No change in size of duct before 20 minutes after secretin administration
image Grade 1 response

– 1 mm dilated duct in only 1 segment of pancreas
– Result is equivocal, and patient probably will not benefit from surgery
image Grade 2 response

– > 2 mm dilated duct in 2 segments of pancreas
image Grade 3 response

– > 2 mm dilated duct in 3 segments of pancreas
image Grade 2 and 3: Patients benefit from surgery

Imaging Recommendations

• Best imaging tool

image Secretin-enhanced MRCP or ERCP

DIFFERENTIAL DIAGNOSIS

Pancreatic Ductal Carcinoma

• When located in head, may mimic divisum on ERCP (or MRCP) with abrupt narrowing and occlusion of ventral duct 

image ERCP and MRCP: PD at site of obstruction appears irregular and abnormally truncated, unlike divisum where ventral duct appears short, but maintains normal branching pattern
• Distinction readily made on CECT or MR, with heterogeneous, hypoenhancing mass in pancreatic head, abrupt obstruction and upstream dilatation of PD, locoregional invasion, and distant metastases

Chronic Pancreatitis

• May result in PD obstruction and upstream dilatation that mimics divisum, with abrupt narrowing and truncation of ventral duct
• Focal or diffuse glandular atrophy with heterogeneous enhancement and dilated, beaded PD

image ± intraductal calculi and parenchymal calcification
image ± focal fibroinflammatory mass that can mimic malignancy
image ± intrapancreatic or peripancreatic pseudocysts
• Thickening of peripancreatic fascia
• ERCP and MRCP: Obstruction and dilatation of PD/radicles

Agenesis of Dorsal Pancreas

• ERCP appearance (with injection of contrast into Wirsung duct) may be identical to pancreas divisum

image Contrast injected into major papilla does not flow past pancreatic head
• Diagnostic key: Absence of pancreatic body/tail on CT or MR

Annular Pancreas

• Congenital anomaly that results in pancreatic tissue partially or completely encircling descending duodenum
• Barium study

image Concentric narrowing of 2nd part with dilated proximal duodenum
image Reverse peristalsis and duodenal ulcer may be seen
• Enlarged pancreatic head encircling 2nd portion of duodenum on CT or MR

image Gastric and duodenal dilatation with circumferential thickening of wall
• ERCP and MRCP: Main PD encircling duodenum and abnormally extending to right side of duodenum

Other Anatomic Variants of Pancreatic Ductal Anatomy

• Multiple configurations of PD are possible, including bifid configuration of dorsal and ventral ducts, duplication anomalies of MPD, ansa pancreatica (duct of Santorini forms sigmoid curve as it joins with ventral duct), and rudimentary or dominant dorsal duct

PATHOLOGY

General Features

• Etiology

image Normal embryology: Ventral pancreas rotates posterior to duodenum and fuses with dorsal pancreas in 8th week of gestation

– Failure of fusion of dorsal and ventral ductal system results in pancreas divisum
– Parenchymal fusion almost always occurs, although there may be textural differences between dorsal and ventral gland, or intervening tissue plane
• Associated abnormalities

image Annular pancreas
image Partial agenesis of dorsal pancreas
image Elevated pressures at sphincter of Oddi
image No definite link with malignancy, although some reports suggest increased incidence of pancreatic cancer, cholangiocarcinoma, and ampullary cancer
• Anatomy of pancreas divisum

image Dorsal PD drains pancreatic anterior head, neck, body, and tail via long and narrow (and sometimes dilated) duct of Santorini into minor papilla

– Poor drainage of secretions from body and tail (as result of relative stenosis at minor papilla) results in increased stasis and ductal pressure → repeated bouts of pancreatitis
– Typically pancreatic head (ventral pancreas) is spared in these bouts of pancreatitis
image Ventral PD drains head and uncinate process via short duct of Wirsung

– Alcoholics may develop pancreatitis due to reflux of bile via short duct of Wirsung

image Body and tail (dorsal pancreas) are spared in such cases due to pancreas divisum

Staging, Grading, & Classification

• May be subdivided into 3 types

image Type I (Classic divisum): No communication between dominant dorsal duct and small ventral duct
image Type II: Duct of Wirsung is completely absent
image Type III (Partial divisum): Small branches of ventral duct may retain communication with dorsal duct
• Reverse divisum: Duct of Santorini does not communicate with main PD

Gross Pathologic & Surgical Features

• Dorsal and ventral pancreatic tissues
• 2 separate duct systems

Microscopic Features

• Normal pancreatic tissue and ductal epithelium
• Inflammatory cells may be present in setting of pancreatitis

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Most cases are asymptomatic
image Epigastric pain, nausea, and vomiting possible due to pancreatitis, with symptoms depending on severity 

– May be induced by overeating or alcohol consumption
– < 5% of patients experience pancreas-related symptoms
image May be seen in multiple family members
• Clinical profile

image Young patient with history of recurrent idiopathic pancreatitis episodes

Demographics

• Age

image Varies widely at diagnosis
image Common between 30-50 years
• Gender

image M > F
• Epidemiology

image Most common congenital anatomic variant of pancreas
image 3-6% of general population

– 4-11% of autopsy series and 3-4% of ERCP series
image May be present in 12-26% of patients with idiopathic recurrent pancreatitis

Natural History & Prognosis

• Complications

image Recurrent pancreatitis (mostly in children)
image Pancreaticolithiasis, serous cystadenoma (speculative)
• Prognosis

image Good, after medical and surgical correction in symptomatic patients

Treatment

• Incidental finding in asymptomatic patient: No treatment
• Symptomatic patients (i.e., repetitive pancreatitis)

image Patients with mild symptoms may be managed conservatively or given pancreatic enzyme therapy
image Severely symptomatic patients may respond to surgical or endoscopic sphincteroplasty/papillotomy of minor papilla

DIAGNOSTIC CHECKLIST

Consider

• Rule out other causes of apparent pancreatic duct obstruction and differentiate from other anatomic variations of pancreatic ductal anatomy

Image Interpretation Pearls

• MRCP and ERCP: Demonstrate short ventral and long dorsal PD with lack of communication between 2 ducts
image
(Left) MRCP shows the main pancreatic duct image entering the minor papilla and the common bile duct image entering the duodenum at the major papilla. The relationship between the pancreatic and common duct is referred to as the crossing duct sign.

image
(Right) Gadolinium-enhanced T1-weighted MR in the same patient demonstrates the main pancreatic duct image entering the duodenum via the minor papilla image. The common bile duct image is seen posteriorly as its enters the duodenum via the major papilla.
image
(Left) Axial CECT shows a dilated pancreatic duct and small pseudocysts image in a patient with pancreas divisum complicated by recurrent episodes of pancreatitis.

image
(Right) More caudal axial CECT in the same patient shows a calculus image within the duct of Santorini, which is of normal caliber downstream as it enters the minor papilla. The stone was confirmed and removed at ERCP, during which a pancreatic stent was also placed.
image
(Left) MRCP shows a dilated CBD image with a distal stricture due to prior pancreatitis. The main pancreatic duct (MPD) image is seen in the body and tail. Note the separate duct of Wirsung image from the head and uncinate, indicating divisum.

image
(Right) MRCP in same patient following administration of secretin shows interval dilatation of the MPD image without fluid accumulating in the duodenum, indicating a stricture at the minor papilla, likely the cause of the patient’s episodes of pancreatitis.
image
ERCP with cannulation of the major papilla shows opacification of the ventral pancreatic duct. The duct is small and short with normal tapering. Note the adjacent acinarization of the pancreatic head.

image
MRCP in a patient with recurrent episodes of pancreatitis shows faintly the ventral duct image with a pancreas divisum configuration of the dorsal pancreatic duct.
image
ERCP in a patient with chronic pancreatis and pancreas divisum shows filling of the ventral pancreatic duct image and a dilated common bile duct image following cannulation of the major papilla.
image
Axial CECT shows a fatty cleft image separating the ventral and dorsal pancreatic segments.
image
Axial curved planar reformation CECT shows the main and dorsal pancreatic ducts image continuing into the minor papilla.
image
A more caudal axial CECT in the same patient shows the ventral pancreatic duct image ending blindly within the head of the pancreas.
image
Coronal CECT demonstrates the common bile duct image extending into the ampulla. The pancreatic duct is not seen extending into the major papilla.
image
Coronal CECT in the same patient demonstrates a mildly dilated dorsal pancreatic duct terminating in the minor papilla image. The dorsal duct was seen to be contiguous with the main pancreatic duct (not shown) and the ventral duct was not visualized, compatible with pancreatic divisum.
image
Coronal MRCP image demonstrates the main pancreatic duct in contiguity with the dorsal duct emptying into the minor papilla image, compatible with pancreatic divisum.
image
Coronal MRCP shows pancreas divisum with the dorsal pancreatic duct image crossing the common bile duct to drain into the expected location of the minor papilla. The diminutive ventral duct is not seen. Note the distended gallbladder image as well as fluid within the duodenum image.
image
MRCP shows the dorsal duct image crossing the common bile duct image to drain into the minor papilla. A small ventral duct image can be seen in the pancreatic head, coursing toward the major papilla. Note also the fluid-filled renal collecting systems image, an occasional source of confusion.
image
MRCP in the same patient following IV injection of secretin shows the duodenum image filling with pancreatic juice. The diameter of the main pancreatic duct image does not change, indicating no functional obstruction.

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