Transient abnormal myelopoiesis accompanied by hepatic fibrosis in two infants with Down syndrome

Two necropsy cases of Down syndrome are reported. These showed transient abnormal myelopoiesis accompanying characteristic hepatic sinusoidal fibrosis. Numerous megakaryocytes were found in the liver of one case, but not in the other. Only eight cases of Down syndrome with simultaneous occurrence of hepatic fibrosis and transient abnormal myelopoiesis have been reported. The cases described here showed slight fibrotic changes in the hyperplastic bone marrow, which were not found in the previously reported cases of transient abnormal myelopoiesis.