Section 4 -

Biopsies for Cholestatic Liver Disease in Infants and Children Valeer J. Desmet Leuven Belgium

Liver biopsy is helpful in the diagnosis of most cholestatic liver diseases in infants and children. The histopathology of "paediatric" cholestasis comprises: 1) features of cholestasis in general; 2) features more specific for the neonatal age; and 3) changes indicative of specific disorders. [1, 2]. 1. Features of Cholestasis in General. Such features include parenchymal changes and periportal / architectural changes. A. Parenchymal changes comprise bilirubinostasis ( hepatocellular , canalicular and in Kufffer cells )in the early stage of complete cholestasis ; cholate stasis of periportal hepatocytes in later stages represented by ballooning , expression of cytokeratin 7 , coarse cytoplasmic granularity , accumulation of copper and copper-binding protein , and development of Mallory bodies ; cholestatic liver cell rosettes corresponding to a switch of hepatocytes from normal plate arrangement into tubular structures with or without bilirubin concrements in the lumen ; occurrence of single and clustered xanthomatous cells ; so-called feathery degeneration ( resembling cholate stasis ) in intralobularhepatocytes ; and in later stages of severe cholestasis : development of paraportal bile infarcts. B. Periportal / architectural changes gradually develop in later stages of chronic cholestatic conditions and comprise : ductular reaction recognized as an increase in ductular structures , associated with oedema and neutrophil infiltration in the periportal region ; development of periductular fibrosis which , together with wedge-like extension of the ductular reaction , results in development of periportal septa that eventually connect adjacent portal tracts , thus creating the pattern of biliary fibrosis and , with addition of nodular parenchymal regeneration , finally biliary cirrhosis . 2. Features Specific for the Neonatal Age. Cholestasis in neonates and young children is usually characterized by the development in hepatocytes of multinucleated giant cell transforrmation (MGCT) and foci of extramedullary hematopoiesis ( either erythropoietic, myelopoietic, thrombopoietic, or all of these together ). 3. Features Indicative of Specific Disorders. Distinction can be made between a) parenchymal disorders ,b) diseases of intrahepatic bile ducts (IHBD), and c) extrahepatic bile duct atresia ( biliary atresia ).Most show some or all of the features of "paediatric " cholestasis in the liver biopsy , some show additional characteristics. A. Parenchymal Disorders. The number of such specific disorders has increased in recent years due to the discovery of responsible gene mutations in several genetic disorders, with concomitant decrease of the category of "cryptogenic cholestasis" [3] . - Bile Acid Synthetic Defects ( BASD) are diagnosed on the base of clinical data ( GGT- and bile acid levels in serum ) , fast atom bombardment - mass spectroscopy ( FAB-MS ) of bile acids , and liver biopsy . MGCT is seen in all symptomatic patients and appears to be more prominent in BASD than in many other forms of neonatal cholestasis; there is generalized hepatocellular injury and progressive periportal fibrosis [4] - Canalicular transporter defects are characterized by lobular bilirubinostasis , variable MGCT, isolated hepatocyte necrosis , and a highly variable rate of progression to cirrhosis. 1)Progressive Familial Intrahepatic Cholestasis type1 ( PFIC type 1 ) and a variant also due tomutation in the FIC1 gene ( Greenland Familial Cholestasis ) show little ballooning , few MGCT , little or no bile duct injury , slow progression of fibrosis , and coarse appearance of bile in canaliculi in electron microscopy ( EM ).A less severe mutation in FIC1 leads to Benign Recurrent Intrahepatic Cholestasis type 1 ( BRIC type 1) with similar histology, absence of lesions between the cholestatic episodes and lack of long term complications. 2)In PFIC type 2 ( Bile Salt Pump or BSEP deficiency ), centrolobular canalicular bilirubinostasis occurs , hepatocyte ballooning and marked MGCT are common , delicate whispy canalicular bile is seen on EM ,and centrolobular and periportal fibrosis with progression to cirrhosis are observed .Negative immunostaining for BSEP is diagnostic. [5] A less severe mutation of BSEP results in recurrent episodes of BRIC type 2 . 3)In PFIC type 3 ( Multidrug Resistance associated Protein 3 or MDR3 deficiency ) there are features of centrolobular bilirubinostasis , some inflammation and hepatocellular injury , damage of interlobular bile ducts , even mild ductopenia and progressive fibrosis leading to cirrhosis.Gamma glutamyl transpeptidase ( GGT ) is increased in serum , in contrast with PFIC types I and 2. [6]. - Cryptogenic neonatal cholestasis still comprises a number of unexplained cholestatic conditions with obscure aetiology , although further recent discoveries continue to reduce this category. Recent examples include, amonst others , the Neonatal Ichthyosis Sclerosing Cholangitis ( NISCH ) syndrome and Arthrogryposis - Renal dysfunction - Cholestasis ( ARC ) syndrome (3). - Intrauterine and perinatal infections or " hepatitis in the neonate " may cause cholestasis , associated with features of hepatitic necro-inflammation , and usually immunohistochemically .demonstrable antigens in the liver biopsy ( e.g. CMV and Herpes hepatitis , viral hepatitis B) - Metabolic disorders causing cholestasis include galactosemia , fructose intolerance and tyrosinemia : characterized by bilirubinostasis, cholestatic rosettes , steatosis , and ductular reaction ; tyrosinemia further shows variable parenchymal siderosis, and regenerative nodules of variable size. Alpha-1-Antitrypsin Deficiency reveals besides " paediatric "cholestasis an accumulation of PAS-positive, diastase-resistant and specific immunoreactive globules in periportal hepatocytes. B. Disorders of Intrahepatic Bile Ducts (IHBD) - Syndromic paucity of IHBD ( or Alagille syndrome ) is recognized by typical clinical features in association with biopsy findings of "paediatric " cholestasis , some ductular reaction and damage is seen in the first 3 months of life . Later biopsies reveal changes of chronic cholestasis and ductopenia. - Nonsyndromic paucity of IHBD shows similar histology , but with persistant ductular reaction and faster development of fibrosis and cirrhosis. C. Biliary Atresia ( BA ) or Extrahepatic Bile Duct Atresia Liver biopsy plays an important role in the diagnosis of BA . Early biopsies in some cases may reveal only non-diagnostic centrolobular bilirubinostasis , necessitating repeat biopsy. In the majority ,diagnostic features are present by ( and even before ) 4 weeks of age ; they consist of changes of " paediatric "cholestasis, and – importantly - , ductular reaction associated with damage of interlobular bile ducts and beginning ductopenia. Later biopsies reveal increasing degrees of fibrosis , duct damage and ductopenia , and rapidly developing cirrhosis. [7] A number of cases ( between 25% and 50% ) show similar lesions , but with bile ducts still in their early embryonic configuration ( so-called ductal plate malformation ) [8] with faster development of fibrosis and cirrhosis and a worse prognosis [9]. References. Desmet V.J. Pathology of paediatric cholestasis. In : Paediatric Cholestasis. Novel Approaches to Treatment. Lentze M.J and Reichen J. eds. Kluwer Academic Publishers .Dordrecht.1992, pp 55-73. Ishak K.G and Sharp H.L. Developmental abnormalities and liver disease in childhood. In: Pathology of the Liver. Fourth edition. MacSween R.N.M., Burt A.D. ,Portmann B.C., Ishak K.G., Scheuer P.J., Anthony P.P. editors.Churchill Livingstone , London ,2002, pp107-154. Carlton VEH et al . Molecular basis of intrahepatic cholestasis. Ann Med ,36 , 606-617, 2004. Bove K.E. et al. Bile acid synthetic defects and liver disease : a comprehensive review. Pediatr Dev Pathol , 7, 315-334, 2004. Keitel V. et al. Expression and localization of hepatobiliary transport proteins in progressive familial intrahepatic cholestasis. Hepatology, 41, 1160-1172, 2005. Balistreri W.F. et al. Intrahepatic cholestasis : summary of an AASLD single topic conference. Hepatology, 42, 222- 235 , 2005. Kahn E. Biliary atresia revisited. Pediat Dev Pathol, 7, 109-124,2004. Desmet V.J. Congenital diseases of intrahepatic bile ducts: variations on the theme " ductal plate malformation". Hepatology, 16,1069-1083,1992. Low Y et al. The prognostic value of ductal plate malformation and other histologic parameters in biliary atresia: an immunohistochemical study. J Pediatr,139,320-322,2001.