非定型的白血病の病態並びに治療に関する研究　第1編　低形成型骨髄造血異常症（Myelodysplasia with Hypoplastic Marrow) の検討

To evaluate characteristics of myelodysplasia with hypoplastic marrow (MDH), clinical and hematological findings in 7 patients with MDH (group A) were compared with those of 23 patients diagnosed with myelodysplastic syndromes (MDS), 13 RAEB and 10 RAEB-T, according to French-American-British co-operative roup classification (group B). Cytopenia and morphological changes in 2 or 3 blood cell lines, corresponding to hematological characteristics of MDS, were observed in all patients in group A. Age distributions and gender ratios did not differ between groups A and B. As the initial symptom, anemia was recognized with a high incidence in both groups. Organomegaly such as hepatomegaly and splenomegaly were observed with nearly equal incidnece in groups A and B. The grades of anemia, leukocytopenia and thrombocytopenia were nearly equal in groups A and B. The percentage of myeloblasts in peripheral blood was higher in group B than that in group A (3.4% versus 0.6%). However, in bone marrow, it was lower in group B than that in group A (11.3% versus 16.5%). The percentage of erythroblasts in bone marrow was lower in group A than group B (17.7% versus 26.6%). Two of 3 patients in group A and 7 of 18 patients in group B showed abnormal karyotypes. The progress from initial symptoms to definite diagnosis ranged from 0.7 months to 38.4 months (mean±SD : 10.1±13.0 months) in group A, and from 0.8 months to 83.3 months (mean±SD : 10.0±18.1 months) in group B, respectively. Four of 7 patients (57%) in group A developed overt leukemia (1 case of hypoplastic leukemia, 2 cases of M2, 1 case of M5b) 1.3～14.3 months after diagnosis of MDH (mean±SD : 8.1±6.5 months), and 9 of 23 patients (39%) in group B also developed overt leukemia (6 cases of M2, 3 cases of M4) 0.5～14.5 months after diagnosis of MDS (mean±SD : 3.8±4.2 months). The median survival time (MST) from the initial symptoms tended to be longer in group A than that in group B (24.2 months versus 18.7 months). The MST from definite diagnosis also tended to be longer in group A than that in group B ( 17.4 months versus 12.1 months). These results suggest that MDH can be included into the clinical entity of MDS in respect to dysmyelopoietic disorders preceeding the onset of acute leukemia.