[Physiopathology of the exocrine pancreas in children]

Abstract

The mechanism leading to exocrine pancreatic disease in children differs from those encountered in adult patients: I. In acute pancreatitis autodigestion of the gland by proteolytic enzymes may occur and two mechanisms may play a role. 1. Reflux of biliary secretions (e.g. in malformations of the duct system) facilitates activation of trypsinogen by enteropeptidase and leads to the presence of active proteolytic enzymes in the gland (exogenous activation). 2. Lysosomal enzymes may play a role in the intracellular activation of zymogens if inflammation leads to a fusion of lysosomes with zymogen granules (endogenous activation). II. In chronic relapsing and hereditary pancreatitis malformations of the pancreatico-biliary duct system must be sought because surgery may be indicated (common channel syndrome and choledochal cysts). III. Among the hereditary diseases leading to pancreatic insufficiency cystic fibrosis (CF) plays the main role. Haplotype analysis has shown that two genetically different types of CF exists (PS and PI). The pancreas shows manifest insufficiency only in the PI-types which occur in more than 70% of cases but the distribution of haplotypes is different in different ethnic groups. In spite of the recent discovery of the cystic fibrosis gene the exact mechanism leading to exocrine pancreatic dysfunction in CF is not clear, but diminished chloride and bicarbonate secretion, may be the result of a disturbance in the regulation of chloride channels, on acinar or ductular level. In the Shwachman-Diamond syndrome a very severe type of exocrine insufficiency with unknown etiology is encountered at birth.