[A study of hypoplastic myelodysplastic syndrome]

To distinguish hypoplastic myelodysplastic syndrome (MDS) from aplastic anemia (AA), morphological abnormalities of bone marrow hematopoietic cells in 8 patients with MDS and 39 patients with AA were studied. All the patients with MDS and AA showed prolonged plasma iron disappearance time, (PIDT1/2) > 120 min. Five hundred erythroid and myeloid cells, as well as 20 megakaryocytes were counted. Dysplastic changes were defined if morphological changes were present in more than 1.0% cells with only one lineage, or in more than 0.6% cells with more than two lineages. Twenty six of 39 patients with AA showed morphological abnormalities. In MDS cases, morphological abnormalities were prominent in trilineage cells in some cases, in bilineage (erythroid and megakaryocytic or myeloid and megakaryocytic cells), in others, or solely in myeloid cells or in megakaryocytic cells in other cases. Morphological abnormalities seen solely in erythroid cells, especially those with segmented nuclei were considered to be less significant for the diagnosis of MDS. The findings were considered to be useful to distinguish hypoplastic MDS from AA.