Pancreatic Pathology Online
Pathology of Heterotopic (Ectopic) Pancreas or Accessory Pancreas
Dr Sampurna Roy MD July 2016
Pancreatic tissue is present outside its normal location.
Heterotopic (ectopic) pancreas, which is incidentally found in 2% of all routine postmortem examinations.
This anomaly is most commonly localized in the wall of the stomach, duodenum and jejunum.
More rarely, it has been found in Meckel's diverticulum of the ileum, the common bile duct, gall bladder, liver, spleen and various other foci in the abdominal cavity.
In the wall of the gastrointestinal tract, pancreatic nodules localize immediately below the mucosa, in the muscularis beneath the serosa, or in small diverticula.
The tissue contains all the components of normal pancreas, namely, acini, ducts, and islets.
The most plausible theories of the origin of Heterotopic pancreas are:
(1) Incomplete atrophy of the left ventral anlage;
(2) Regression to a more primitive pattern of differentiation reminiscent of that seen in lower vertebrates, especially certain fish in which exocrine and endocrine pancreatic tissue are diffusely distributed in liver, intestinal wall, and peritoneum;
(3) Inappropriate expression of the pleuripotent developmental capacity of the embryonic gut;
(4) Buds of embryonic pancreatic tissue that have penetrated the intestinal wall and have become isolated from the main mass and thus misplaced by rapid longitudinal growth of the intestine.
Of these theories, the last two (3) and (4) seem more probable.
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