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Pancreatic duct and variations

Dr Yuranga Weerakkody and Dr Frank Gaillard et al.

The pancreatic ductal embryology is moderately complicated, leading to a number of anatomical variants of its ducts, many of which are clinically significant.

The normal arangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vater through the sphincter of Oddi.

There are two main end ducts within the pancreas

Duct of Wirsung

embryologically is the dorsal bud duct (which goes on to part of the head and uncinate process of the pancreas).
drains at the ampulla of Vater.
connects with the duct of Santorini to form the main pancreatic duct (contributes the head portion).

Duct of Santorini

embryologically is the ventral bud duct (which goes on to part of the head, body and tail of the pancreas).
drains at the minor papilla if present.
connects with the duct of Wirsung to form the main pancreatic duct (contributes the body and tail portion).

Variations

Pancreas divisum

A pancreas divisum is the most common variation of pancreatic duct formation and can account for up to 14 % ³. It results from failure of fusion of dorsal and ventral pancreatic anlages. As a result, the dorsal pancreatic duct drains most of the pancreatic glandular parenchyma via the minor papilla. Although controversial, this variant is considered as a cause of pancreatitis^1,3.

Pancreatic divisum can result in a santorinicele ², which is a cystic dilatation of the distal dorsal duct, immediately proximal to the minor papilla .

Three sub types are known

type 1 : classic : no connection at all : occurs in the majority of cases : ~ 70% ⁵
type 2 : absent ventral duct : minor papilla drain all of pancreas while major papilla drains bile duct : ~ 20 - 25 % ⁵
type 3 : functional : filamentous or inadequate connection between dorsal and ventral ducts : ~ 5 - 6 % ⁵

Annular pancreas

An annular pancreas is an uncommon ( ≈ 1 in 20000 ¹) variation with partial or complete surrounding of the duodenum with pancreatic tissue. The ventral pancreatic "anlage" is responsible for this anomaly by dividing early into 2 segments.

often detected incidentally in asymptomatic patients
may be associated with duodenal stenosis, postbulbar ulcerations, pancreatitis or biliary obstruction

Bifid pancreas

Rare branching anomaly of the pancreas tail and its duct system, also known as fishtail pancreas⁶.

Ectopic pancreatic tissue

Ectopic pancreatic tissue refers to pancreatic rests that lie outside and separate to the pancreatic gland. It is reportedly quite common, affecting 1 - 10% ¹ of people, most of whom are completely asymptomatic.

Recognised locations for ectopic pancreatic tissue include the gastic antrum, proximal duodenum, ileum and Meckel's diverticulae.

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