Clinical and laboratory features of de novo acute myeloid leukaemia with trilineage myelodysplasia.

Primary myelodysplastic syndromes progress to acute myeloid leukaemia (AML) in about 30% of cases. We have sought evidence of pre-existing trilineage myelodysplasia (TMDS) using the FAB criteria (1982) in 160 consecutive cases of primary de novo AML. TMDS was found in 24 cases (15%) including two of 33 cases of M1 (6%), four of 40 cases of M2 (10%), none of 18 cases of M3, five of 31 cases of M4 (15%), six of 30 cases of M5 (20%), all of six cases of M6 and one of two cases of M7. The median presentation bone-marrow blast-cell count in the 24 AML/TMDS cases was 53% (30-90%) and 82% (45-100%) in the 136 cases of AML without TMDS. 60% of the AML/TMDS bone-marrow aspirates contained fewer than 60% of blasts compared with only 11% of those from AML without TMDS (P less than 0.001). In AML the occurrence of symptomatic cytopenias when the marrow blast-cell count is below 60% and the peripheral blood blast-cell count is below 20% is highly correlated with dysplastic haemopoiesis (P less than 0.001).