Acute pancreatitis with pancreas divisum

Clinical History

A 71-year-old patient, complaining of epigastric pain was referred to our radiology department. A diagnosis of acute pancreatitis was made due to the elevated levels of serum amylase and lipase. There was a past history of a similar episode two years prior to the actual presentation.

Imaging Findings

CT of the abdomen with contrast was performed and showed diffuse oedema of the pancreas with peripancreatic inflammatory changes; consistent with acute pancreatitis. No evidence of complication.
MRI confirmed the findings shown on CT. The MRCP sequences excluded the presence of stones along the common bile duct, which drains via the major papilla. The pancreatic duct was seen to be draining into the duodenum via the minor papilla.

Discussion

The main pancreatic duct (of Wirsung) joins the bile duct to drain into the duodenum via the major papilla. The accessory duct (of Santorini), which may be absent, drains via the minor papilla, lying 2 cm cranial to the major papilla [1].

The Pancreas develops by fusion of two buds: The ventral bud (that later forms the uncinate process and the head), which drains via the major papilla, and the dorsal bud (that later forms the body and tail), which drains via the minor papilla [2]. During the fourth gestational week, the dorsal bud is found to the left and the ventral bud to the right of duodenum. During the sixth week the ventral bud rotates posterior to the duodenum and fuses with the dorsal bud during the seventh week. After fusion, the pancreas drains through the ventral duct into the major papilla, while the distal segment of the dorsal duct regresses, forming the accessory duct of Santorini, which may be partially or completely obliterated and drains into the minor papilla [2, 3].

Incomplete fusion of the ventral and dorsal buds will cause a persistence of the embryological status, leading to the draining of the body and tail (dorsal bud) through the duct of Santorini; via the minor papilla, and also the draining of the uncinate process and head (ventral bud); through the duct of Wirsung via the major papilla. This is known as pancreas divisum, and is the most common congenital anatomical variant; involving 4-14% of the population on post-mortem [4]. The term, incomplete pancreas divisum, is given when there is only a tiny communicating branch between the two ducts [5,6].
Most patients are asymptomatic [4]. The poor drainage of pancreatic secretion into the minor papilla will lead to increased stasis and ductal pressure, which may cause pancreatitis. 12-26% of patients with idiopathic recurrent pancreatitis show the presence of pancreas divisum [2]. No association with biliary duct malignancies were found [5].

MRCP is a non-invasive method that allows delineation of the ductal anatomy and can be used to exclude other causes of ductal obstruction. MRI allows for detection of extra-ductal diseases; which is one of the advantages over ERCP [2].
Symptomatic cases may be treated by sphincterotomy, stenting or balloon dilatation of the minor papilla [7].

Take home message:
Pancreas divisum is a benign disorder with increased risk of pancreatitis [8]. It should be investigated in cases of pancreatitis with unknown cause.

Differential Diagnosis List

Final Diagnosis

Acute oedematous pancreatitis with pancreas divisum.

URL:	https://eurorad.org/case/11597
DOI:	10.1594/EURORAD/CASE.11597
ISSN:	1563-4086