The significance of trilineage myelodysplasia in de novo acute myeloblastic leukemia: clinical and laboratory features.

A prospective study was undertaken to elucidate the clinical and laboratory differences between de novo acute myeloid leukemia (AML) and AML with trilineage myelodysplasia (AML-TMDS). One hundred and seven patients with AML were diagnosed at the University Hospital between January 1987 and July 1992, and were followed until July 1995. TMDS was identified in 17 of them (16%). With regard to age and sex distribution no difference was found between AML patients with and without TMDS (p = 0.43, p = 0.54, respectively). The duration of symptoms at presentation in AML-TMDS was similar to those observed in de novo AML (p = 0.29). Hemoglobin values and platelet counts were similar in both groups of patients (p = 0.45, p = 0.44, respectively). However, peripheral white blood cell and neutrophil counts, as well as blast counts in AML-TMDS patients were lower than those observed in AML without TMDS patients (p < 0.001 for all of them). Bone marrow blast counts in de novo AML were higher than the values observed in AML-TMDS patients (p < 0.001). TMDS occurred predominantly in M2 and M6 FAB types, and was absent in the M3 type. Bone marrow histology showed no particular feature that could be of diagnostic relevance. The remission rates were similar in both groups of patients (p = 0.55). The same was true for the probability of disease-free survival and overall survival during the period of study (p = 0.50, p = 0.33, respectively). These results suggest that: 1) in AML-TMDS patients, leukemia transformation occurs in a more undifferentiated pluripotent stem cell, leading to a dysplastic residual hemopoiesis besides the blast proliferation; 2) the incidence of TMDS in our group of patients did not influence the clinical outcome after treatment of the disease.