The hepatic lesion in Reye's syndrome.

The hepatic lesion in Reye's syndrome (acute encephalopathy with fatty degeneration of viscera) was studied by light microscopy of sequential biopsy specimens obtained in 49 children. The hepatic lesion is a morphologically characteristic, rapidly evolving, and reversible toxic hepatitis. In specimens obtained with 48 hr of onset of neurological deterioration, the severity of the diffuse microvesicular steatosis is best appreciated in frozen sections stained for lipid content. Variation in severity of hepatocyte glycogen depletion in early biopsies correlates with other histological measures of severity, and with the occurrence of hypoglycemia, severity of the encephalopathy at the time of admission, and mortality rate. Histochemical studies suggest that the hepatic lesion is attributable to mitochondrial injury and other evidence that supports this hypothesis is briefly reviewed. The etiology of the syndrome and its relationship to the viral disease which usually precedes it are unknown.