[Evolution of acute leukemia in myelodysplastic syndromes: prognostic histopathological factors in a series of bone marrow biopsies]

Out of 9,324 bone marrow biopsies, 250 cases of myelodysplastic syndromes (MDS) and 514 of acute non-lymphoid leukemia (AL) were collected. Twenty AL represented an evolution of MDS: the marrow had a mean cellularity of 58.5%, a mean percentage of blasts of 19% (55% of the cases had more than 10% of blasts in the marrow); only in one case (5%) benign lymphoid nodules (LN) were present. In 42 cases of MDS deceased without an evolution to overt AL, the bone marrow showed a cellularity of 60%, a mean percentage of blasts of 14% (only 29% had more than 10% of blasts); in 13 cases (31%) LN were present. Our data indicate that the percentage of bone marrow blasts is the most significant criterion for predicting an evolution to AL, although in the single case such evolution is not foreseeable. The presence of LN mostly in MDS without a leukemic progression could indicate a protective effect of NL, perhaps by means of an immunologic mechanism.