Classic syndrome involves combination of resolving viral illness and salicylate therapy
Etiology/Pathogenesis
• Pathogenesis unknown
• Mitochondrial injury is a key feature
• Frequent antecedent viral infection
• Salicylate exposure appears to play role although no causal connection proven
Clinical Issues
• Clinical picture dominated by neurologic rather than hepatic manifestations
Clinical evidence of hepatic disease may be very subtle
• Biphasic pattern: Viral prodrome followed by neurologic manifestations
Prodromal febrile illness
Vomiting and neurologic alterations 3-5 days later
• Mortality ∼ 30%
Death usually due to cerebral edema and complications
Microscopic
• Diffuse, panlobular microvesicular steatosis
• No significant inflammation
Top Differential Diagnoses
• Congenital metabolic conditions
• Acute fatty liver of pregnancy
• Alcoholic foamy degeneration
• Drug/toxin-mediated injury
• Sepsis
Diagnostic Checklist
• Presumptive diagnosis can be made based on clinical and laboratory findings
• Microvesicular fatty change in context of neurologic alterations/encephalopathy
• Necessity of liver biopsy for diagnosis is controversial
Microvesicular Steatosis Diffuse microvesicular steatosis and occasional acidophil bodies are seen in a case of Reye syndrome. Cholestasis is rare in this disorder.
Absence of Portal Inflammation An intact portal tract with no portal inflammation is seen in a biopsy from a patient with Reye syndrome. Portal inflammation is typically absent. Diffuse background microvesicular steatosis is also seen.
Microvesicular Steatosis Microvesicular steatosis is characteristic of Reye syndrome. Numerous tiny fat vacuoles surround the hepatocyte nucleus , which retains its central location within the hepatocyte. This change can be subtle and may be mistaken for hepatocyte swelling or an artifact.
Microvesicular Steatosis on Electron Microscopy This electron micrograph shows numerous lipid droplets within a hepatocyte in a patient with Reye syndrome. (Courtesy E. Sengupta, MD.)
TERMINOLOGY
Definitions
• Acute and potentially life-threatening disorder characterized by fatty liver and encephalopathy
Most common in infants and children under 17 years
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