Introduction

Neonatal hepatitis refers to a heterogeneous group of disorders that result in a somewhat similar morphologic change in the liver of an infant younger than 3 months of age in response to various insults. The term neonatal hepatitis has been used at times to include all causes of cholestasis in infancy in which extrahepatic biliary obstruction is excluded. Although in the majority of cases an etiology cannot be found, specific infectious and metabolic causes have been identified that may present as neonatal hepatitis. At final diagnosis, neonatal hepatitis is responsible for approximately 40% of the cases of infants with cholestasis and is the most frequently encountered liver disorder of early infancy. Males usually predominate over females (2:1). Additionally, some familial cases have been reported, suggesting either a maternal environmental factor or autosomal recessive inheritance.

Histologically, there is a loss of the lobular architecture with preservation of the zonal distribution of portal tracts and central veins. There is ballooning degeneration of hepatocytes with fusion of hepatocyte membranes and nuclear transformation into multinucleated giant cells. These multinucleated giant cells are believed to be the response of immature hepatocytes to most forms of injury and are a non-specific finding in neonatal liver biopsy samples. There may be abundant extramedullary hematopoiesis and variable inflammation (Figure 10.1). Cholestasis may be marked because the newborn already is in a relative state of physiologic cholestasis. Finding cytoplasmic inclusions, steatosis, or storage material, or elucidating a positive family history, may aid in distinguishing metabolic, viral, and familial causes of neonatal hepatitis.