Extrahepatic Bile Duct Atresia From The Pathologist'S Perspective: Pathological Features And Differential Diagnosis

Extrahepatic biliary atresia (EHBA) refers to stenosis or atresia of the extrahepatic biliary tree. It accounts for 25-30% of cases of neonatal cholestasis. If left untreated, EHBA progresses to biliary cirrhosis and is universally fatal within the first 2 years of life. Early diagnosis is crucial since surgical treatment (Kasai procedure) is the only treatment option. Histopathologic examination of liver biopsy specimens is a key element in the diagnostic work-up of infants with suspected EHBA. Pathologic diagnosis aims at excluding non-surgically correctable causes of neonatal cholestasis thereby leading to surgical exploration for confirmation of the diagnosis. All published data indicate that pathologists can diagnose EHBA with high sensitivity, high specificity and reasonable interobserver agreement. The most useful histologic features in the diagnosis of EHBA are portal tract changes including ductular proliferation and bile plugs in ducts and ductules. These lesions are not pathognomonic but can be seen in extrahepatic obstruction of any cause. Total parenteral nutrition (TPN)associated cholestasis and alpha1-antitrypsin (A1AT) deficiency cannot be differentiated from EHBA without access to clinical data and may lead to false-positive diagnosis. False-negative interpretation may be caused by early age at diagnosis or by small/indequate specimens. The pathologist also plays a role in the examination of the resected fibrotic segment and of explant specimens. Histopathology can yield prognostic information, being also an indispensable tool in research for the possible pathogenesis of this disease. A well-coordinated, multidisciplinary approach is required in the assessment of suspected cases of EHBA.