[Unusual hepatic fibrosis in three cases of Down syndrome]

We report three infants with Down syndrome who had hepatic fibrosis, which is rare in this syndrome. Liver specimens were obtained by biopsy or autopsy. In one patient, the peripheral blood contained blastoid cells, a typical hematological feature of the transiently abnormal myelopoiesis of Down syndrome. Ascites and hepatosplenomegaly were found in all patients. The intralobular hepatic fibrosis was pericellular and perisinusoidal, and the narrowing of the central veins resembled that in venoocclusive disease of the liver. We found some megakaryocytes in the liver, which were stained for von Willebrand factor and platelet glycoprotein IIb/IIIa. In one specimen, collagen type IV and alpha smooth muscle actin were stained by immunohistochemical methods, so the fibrosis in this case was probably caused by cells such as Ito cells derived from myofibroblasts. Overall, the findings suggest that megakaryocytes in the liver of these three patients produce collagen-stimulating cytokines such as transforming growth factor beta, and that Ito cells were involved in the hepatic fibrosis we observed.