CLINICAL AND CYTOGENETIC FINDINGS OF MYELODYSPLASTIC SYNDROMES SHOWING HYPOCELLULAR BONE-MARROW OR MINIMAL DYSPLASIA, IN COMPARISON WITH TYPICAL MYELODYSPLASTIC SYNDROMES

Hematologic and cytogenetic data were collected on 401 myelodysplastic syndromes (MDS) patients in Japan and their clinical relevance was an alyzed. More than 50% of the MDS patients with hypocellular bone marro w had > 5% marrow blasts at the time of MDS diagnosis and frequently h ad complex aberrations (chromosome changes at three or more regions). They showed peripheral blood findings resembling those of aplastic ane mia, but progression into leukemic phase and the prognosis tended to m imic typical MDS. In MDS patients with minimal dysplasia, hematologic parameters were different from those of aplastic anemia. However, the low incidence of leukemic transformation and the favorable prognosis w as similar to that of aplastic anemia. More than 90% of the patients i n this group had refractory anemia and had normal karyotypes. Thus dif ferential diagnosis from a low grade aplastic anemia is important, sin ce this type of MDS might have a clonal nature as well. In conclusion, although some hematologic and clinical deviations are noticed in MDS with hypocellular marrow or minimal dysplasia, these MDS subtypes migh t constitute marginal forms of MDS.