Reye's syndrome - histological finding
Glycogen depletion Histology of the liver on Reye's syndrome: Histology of the liver shows diffuse microvesicular steatosis (fatty vacuolization) with minimal inflammatory changes. Glycogen is viually absent from the hepatocytes in biopsy specimen. Mitochondrias are large pleomorphic and have decreased matricial density on electron microscopy. The kidney changes include swelling and fatty degeneration of proximal tubules. Astrocyte edema and loss of neuron in the brain. Reyes syndrome It is an acute self limiting metabolic insult of diverse etiology resulting in generalised nzitochondrial dysfunction due to inhibition of fatty acid )8 oxidation. Salicylates or viral infection can precipitate this metabolic impairment. The pathogenesis is thought to be damage to mitochondria caused by salicylate metabolite or some other toxin or chemical in the setting of viral infection. The reasons for mitochondria' dysfunction are unknown. No toxic factor has yet been conclusively identified but studies have suggested an etiological link among Reye's syndrome. The activities of hepatic mitachondrial enzymes including ornithine transcarbamylase, carbamoyl phosphate synthetase and pyruvate dehydrogenase are reduced often to less than half their normal values. Mitochondria' dysfunction leads to elevated sho chain fatty acids and hyperanzmonenzia as well as directly to cerebral edema. It is prudent to avoid the use of aspirin as an antipyretic in pediatric patients with influenza or varicella. Clinical manifestations:- Classic Reyes syndrome exihibits a stereotypic biphasic course. It usually occurs in a previously healthy child. A prodromal febrile illness, an upper respiratory tract infection or chicken pox is followed by an interval in which the child has seemingly recovered. The abrupt onsent of protracted vomiting then occurs usually within 5-7 days after the onset of viral illness. Delirium, combative behaviour and stupor may occur simultaneously within a few hours after the onset of vomiting. Neurological symptoms may rapidly progress to seizures, coma and death; focal neurological signs are absent. Laboratory features:- There is explosive release from liver and muscle of enzymes such as aminotransferases, creatine kinase and lactic dehydrogenase. The activity of the mitochondrial enzyme serum glutamate dehydrogenase is greatly increased. Serum Ammonia level is increased. The prothrombin time is mild to moderately increased.
Budding and branching of mitochondria
Swelling of endoplasmic reticulum
Paranuclear microdense deposits
Glycogen depletion