Liver ultrastructure in abetalipoproteinemia: Evolution of micronodular cirrhosis.

Abstract

An infant was found to have abetalipoproteinemia, substantial hepatomegaly, and persistent elevation of the serum transaminases. Liver biopsies were obtained prior to treatment with medium chain triglyceride (MCT) and at 2, 14, and 20 months after initiation of treatment with the MCT-substituted low fat diet. The initial liver biopsy contained 38% lipid, 91% of which was triglyceride. The hepatocytes contained large fat droplets which ruptured to form centrilobular fatty lakes. Ultrastructurally, the Golgi was nearly completely deficient in trans-Golgi vacuole formation. Endogenous triglyceride particles could not be found, and the circum-Golgi smooth endoplasmic reticulum was absent. When the infant was fed a medium chain triglyceride diet, steatorrhea improved and the liver cell cytoplasmic fat droplets became smaller and less numerous. During the 14 months of MCT feedings, however, there was progression of the initially mild hepatic fibrosis to an advanced micronodular cirrhosis, and alcoholic hyalin appeared in the hepatocytes. It is speculated that the evolution of alcoholic hyalin may be related to the accumulation of 2-carbon fragments derived from MCT in the face of defective hepatic triglyceride secretion. Because of the destructive but asymptomatic lesion in this infant’s liver, liver function should be carefully investigated in all children with abetalipoproteinemia. Diagnostic liver biopsy is indicated if hepatomegaly or chemical signs of liver dysfunction persist, particularly if diet manipulation is contemplated.