HISTOPATHOLOGICAL FINDINGS IN A MALE WITH LATE-ONSET ORNITHINE TRANSCARBAMYLASE DEFICIENCY

Late onset of symptoms in a 12 1/2-year-old male with ornithine transc arbamylase (OTC) deficiency were associated with unusual histological features in the liver. The patient presented with an acute onset of hy perammonemia and altered mental status after a 2-day prodrome of vomit ing and lethargy. Physical examination showed a combative and disorien ted male with icteric sclerae but with no fever or hepatomegaly. The p lasma ammonia level was 282 muM. Enzyme assays of liver tissue obtaine d by percutaneous needle biopsy showed OTC activity of approximately 3 % of normal; carbamyl phosphate synthetase was normal. Histopathologic al findings included severe microvesicular centrilobular steatosis. He patic architecture and reticulin framework were well preserved. Many h epatocyte nuclei were filled with glycogen. Electron microscopy showed mitochondria that were rounded and expanded with cristae at the edge of the mitochondrial membrane. In contrast to other reports, only slig ht variations in size and shape were seen. Megamitochondria and intram atrical paracrystalline inclusions were not identified. The cytoplasm contained scattered fat globules, peroxisomes, and dilated smooth endo plasmic reticulum. The prominent mitochondrial abnormalities commonly found in OTC deficiency were notably absent.