Mitochondrial enlargement and crystalloid matrix arrays: distinctive finding in childhood portal hypertension due to cavernous transformation of the portal vein.

Elongated, enlarged mitochondria with crystalloid matrix arrays were discovered in periportal hepatocytes in 11 of 12 children (age 6 to 15 years) with portal hypertension, minimal alterations on light microscopy, and cavernous transformation of the portal vein. Eleven of the children were clinically well before onset of symptoms, one was anemic with megaloblastic bone marrow, and a second had undergone renal transplantation. Minimal findings by light microscopy included slight portal fibrosis (six cases), pericentral venular fibrosis (one case), mild, patchy sinusoidal sclerosis (one case), central venular and sinusoidal dilatation (two cases), and mild hepatocellular lipid accumulation (one case). Four were judged normal by routine histologic examination. Subtle depletion of periportal hepatocellular glycogen was present in six. In 10, subtle striation or granularity of periportal hepatocyte cytoplasm was visible with high-magnification light microscopy. Although similar mitochondria are seen sporadically in hepatocytes in diverse settings, enlarged mitochondria with crystalloid matrix inclusions have not been previously reported as a uniform feature in children with portal hypertension due to cavernous transformation of the portal vein and minimal other hepatic alteration. It is postulated that the mitochondria are adapting in response to an abnormal metabolic milieu created by hemodynamic alterations.