Congenital hepatic pancreatic and biliary abnormalities

Abnormalities of the hepaticopancreaticobiliary system are all extremely rare. They are included here as knowledge of their existence is important, as they form part of the differential diagnosis for infants with jaundice, malabsorption and hypo-glycemia.

The most common lesions of the biliary tree are biliary atresia and congenital biliary dilatation. In biliary atresia the biliary tree is obliterated either completely or partially. Congenital biliary dilatation includes a variety of abnormalities of the biliary tree in which the dilated segment may be either intrahepatic or extrahepatic and either fusiform or cystic in nature. Dilatations of the extrahepatic biliary ducts are commonly known as choledochal cysts. The dilated bile duct is both anatomically and functionally abnormal, resulting in cholestasis. Infants with biliary atresia and severe cholestasis associated with biliary dilatation present in the neonatal period with prolonged jaundice due to accumulation of conjugated biliru-bin. When the degree of obstruction to the biliary tree is not so severe, congenital biliary dilatation may present later in life with malabsorption, intermittent jaundice, abdominal pain or even pancreatitis. In addition, a choledochal cyst may present as an upper abdominal mass. Treatment of these lesions is centered around allowing drainage of the biliary tree into the intestine, and the surgery involved is often complex. The operation of choice for biliary atresia is the Kasai portoenterostomy.23 The atretic remnants of the extrahepatic biliary ducts are removed and the porta hepatis is anastomosed to a defunctioned loop of jejunum. The timing of surgery is of paramount importance to avoid hepatocellular damage, but even with prompt diagnosis and early surgical intervention infants with biliary atresia often have residual hepatic impairment due to intrauterine cholesta-sis. In cases of choledochal cysts the dilated portion of the extrahepatic ducts are removed together with the gallbladder, and the common hepatic duct is anastomosed to the duodenum or a defunctioned loop of jejunum.

There are a number of congenital hepatic anomalies that give rise to structural and/or functional abnormalities of the liver parenchyma or the intra-hepatic biliary tree. These include infantile and adult-type polycystic disease, congenital hepatic fibrosis, biliary hypoplasia and congenital tumors of the liver such as hamartomas and heman-giomas. Presentation is usually with one of hepatomegaly, portal hypertension or cholangitis. Treatment is that of resection of suitable lesions and prevention or treatment of hepatic disease.

Congenital lesions involving the pancreas are rare, the most common being annular pancreas (see the section on the duodenum p. 00). Other anatomical anomalies are seen including pancreatic ductal anomalies, pancreatic cysts and very rarely pancreatic agenesis. There are a group of infants who present in the neonatal period with hypoglycemia who are found to have inappropriately high levels of circulating insulin. The condition hyperinsu-linemic hypoglycemia (previously commonly referred to as 'nesidioblastosis') is characterized by inappropriate endogenous insulin secretion in the presence of low blood glucose. It may result from an insulin-secreting tumor in the pancreas (a so-called 'insulinoma') but more commonly no tumor is identified and the disease is a result of a genetic defect in a membrane channel controlling insulin secretion. Infants require high glucose intake to maintain normoglycemia whilst they are investigated for the presence of an isolated secretory tumor. Treatment is by surgical excision of the tumor if present, otherwise a 90-95% subtotal pancreatectomy is performed.

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