Histological and cytogenetic characterization of bone marrow in relation to prognosis and diagnosis of myelodysplastic syndromes.

Bone marrow (BM) histology of 102 myelodysplastic syndromes (MDS) patients was analyzed retrospectively. All the cases were reclassified according to the World Health Organization (WHO) classification. Karyotype study was conducted for all except one. Fifteen of the MDS cases were hypoplastic. The cellularity in bone marrow histology is sometimes ineffective in the differential diagnosis of MDS and aplastic anemia (AA). Nonetheless, a marked decrease in the number of megakaryocytes (average, 0.3/mm(2); range, 0-2/mm(2)) even in the hyperplastic foci of the marrow of AA was the most important histological feature differentiating AA from MDS, whereas the number of megakaryocytes increased in most MDS cases (44/mm(2); range, 1-240/mm(2)) and also in hypoplastic MDS (14/mm(2); range, 8-26/mm(2)). Hyperplastic marrow had a significantly high frequency of progress to acute myeloid leukemia (AML) and hypoplastic MDS had a lower rate of progress to AML. Severe myelofibrosis had a significantly poor prognosis. An increase in CD34-positive cells in MDS indicated a high rate of progress to AML. As for the patients with refractory cytopenia with multilineage dysplasia (RCMD; the new category under the WHO classification), the increased number of megakaryocytes was correlated with poor prognosis.