Congenital Anomalies of the Pancreas
Developmental variants of pancreatic anatomy arising from abnormal fusion or rotation of the dorsal and ventral pancreatic buds during embryogenesis. Most are incidental findings; a minority cause clinically significant disease, principally recurrent pancreatitis.
Pancreas divisum: failure of fusion of the dorsal and ventral pancreatic ducts, the commonest congenital pancreatic anomaly (present in 5-10% of the population).
The dorsal duct (of Santorini) drains the bulk of the gland through the smaller minor papilla rather than the major papilla. Relative outflow restriction through this narrow orifice is proposed as a cause of recurrent idiopathic pancreatitis in a subset of affected individuals.
Most people with divisum never develop symptoms, so the anatomical finding alone does not equal the diagnosis.
Annular pancreas: a ring of pancreatic tissue encircling the second part of the duodenum, causing duodenal obstruction. Presents in infancy with bilious or non-bilious vomiting (depending on whether obstruction is pre- or post-ampullary) or, in adults, incidentally or with recurrent pancreatitis or peptic ulceration from duodenal stasis. Associated with Down syndrome, duodenal atresia, and other structural anomalies.
Ectopic (heterotopic) pancreas: pancreatic tissue outside its normal location, most often in the stomach, duodenum or Meckel diverticulum, usually asymptomatic and found incidentally, occasionally causing bleeding, obstruction or intussusception if large, and rarely undergoing malignant transformation.
Pancreatic agenesis and hypoplasia: rare, associated with severe exocrine and endocrine insufficiency from birth (neonatal diabetes), often with other congenital anomalies.
