[Morphological observation of a process of bone marrow hypoplastic formation in a case of aplastic anemia].

Bone marrow morphological change was consecutively analyzed form the disease onset to the formation of bone marrow aplasia in a patient with post-hepatitic aplastic anemia. In this case, the mean bone marrow cellularity and absolute numbers of erythroids and megakaryocytes were continuously higher than those in normal subjects for 3 weeks after the appearance of peripheral pancytopenia. During this stage, administration of recombinant human granulocyte colony-stimulating factor (G-CSF) improved marrow myeloid hypoplasia and peripheral neutropenia. During the period in which the marrow cellularity transformed from hyperplasia to hypoplasia, the bone marrow showed a mixture of hyper-, normo- and hypocellular portions, and the decrease in the megakaryocytes was the faster than myeloid and erythroid cells. These findings indicate that (1) ineffective hematopoiesis might be present in the early stage of the disease, (2) G-CSF responsive granulocytic precursors remained during the early stage of the disease, and (3) the marrow aplasia progressed in the manner of aplastic nest formation during the period in which the marrow cellularity declined to hypoplasia. We experienced another case of aplastic anemia showing the same progress of bone marrow findings and speculated that this might be one of the ways of the progression of bone marrow hypoplastic formation in aplastic anemia.