Once known etiologies are excluded, then considered idiopathic
• By mid-2000s, idiopathic neonatal hepatitis (INH) comprised only 15-30% of neonatal cholestasis due to increased ability to detect and diagnose metabolic and genetic disorders previously considered idiopathic
Clinical Issues
• Jaundice
• Hepatomegaly ± splenomegaly
• Bruising/bleeding due to vitamin K deficiency
• Elevated serum total and conjugated bilirubin
• Variably elevated transaminases
Microscopic
• Lobular disarray with giant cell transformation
• Canalicular and hepatocellular cholestasis
• Minimal portal changes
• Preserved bile ducts
• Prominent extramedullary hematopoiesis
Top Differential Diagnoses
• Exclude biliary atresia right away because it requires early surgical intervention
• If neonatal hepatitis-like pattern of injury present, use clinical information and molecular tests to exclude known disorders
INH is diagnosis of exclusion
Lobular Giant Cell Change and Extramedullary Hematopoiesis The characteristic features of idiopathic neonatal hepatitis include lobular giant cell transformation and prominent extramedullary hematopoiesis. Portal changes are minimal, and ductular reaction is absent.
Cholestasis and Giant Cell Transformation The lobular hepatocytes show giant cell change and scattered apoptotic hepatocytes , along with canalicular cholestasis and a cholestatic rosette .
CMV Infection This case of neonatal hepatitis due to CMV shows a few giant cell hepatocytes along with extramedullary hematopoiesis. A single CMV inclusion was identified.
Biliary Atresia May Mimic Neonatal Hepatitis This biopsy from a 9 week old with biliary atresia has features similar to idiopathic neonatal hepatitis, such as giant cell change, but also contains expanded portal tracts with associated ductular reaction.
TERMINOLOGY
Abbreviations
• Idiopathic neonatal hepatitis (INH)
Definitions
• General term for clinical condition manifested by prolonged jaundice in neonates with variable but definable histologic picture
Clinicopathologic picture is termed neonatal hepatitis syndrome
– Uniform clinical presentation but broad spectrum of causative disease processes
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, along with canalicular cholestasis and a cholestatic rosette 
.
was identified.
