Electron microscopic changes in the liver in Reye's syndrome

Abstract

Reye's syndrome is acute encephalopathy in children associated with fatty liver. Lover cells are filled with fat droplets throughout the lobule; there is no inflammation. We hae examined the electrom microscopic (EM) changes in 16 children with Reye's syndrome. Diagnostic Menghini needle biopsies were obtained 6 hours to 4 days after onset of centrl nervous system signs; follow-up biopsies were obtained 2 months later from 7 of 9 survivors. Distinctive mitochondrial changes were present in all initial biopsy specimens: The matric was distended (greatly in severe cases) and matrix protein was disorganized. Cristae were disrupted. The swollen mitochondria assumed bizarre contours. In two cases with severely altered mitochondria in the initial biopsy who were treated by exchange transfusion, most but not all mitochondria were normal by 2 months. One of these biopsied on the 3rd day, after onset of CNS signs and 6 exchange transfusions, showed great improvement in mitochondrial morphology. In early biopsy speciments the smooth endoplasmic reticulum (ER) was hypertrophied; in well glycogenated cells extensive “glycogen body” formation was seen. In fatal cases, glycogen depletion was severe. Peroxysomes were increased in all biopsy specimens. In less severe cases there was active peroxysome proliferation from smooth ER. Peroxysome proliferation may represent a compensatory response to deficient mitochondrial respiration. In recovery, rough ER was increased and its cisternae were distended. The Golgi system was hypertrophied with lipid filled saccules. The EM changes show that potentially reversible mitochondrial injury is a main feature of the liver lesion in Reye's syndrome. The etiologic agent may be a mitochondrial toxin.