Remission with morphological myelodysplasia in de novo acute myeloid leukaemia: implications for early relapse.

Myelodysplastic features of remission bone marrow were investigated in 46 adults with de novo acute myeloid leukaemia (AML) according to the FAB morphological criteria for myelodysplastic syndromes (MDS). Compared with a group of 18 patients with the common type of acute lymphoblastic leukaemia in remission, micromegakaryocytes (30.4% v. 5.6%, P less than 0.05), multi-separated nuclear megakaryocytes (45.7% v. 0%, P less than 0.01), degranulated neutrophils (39.1% v. 5.6%, P less than 0.05), and neutrophils with hyposegmented nuclei (34.8% v. 0%, P less than 0.01) were significantly more common in the AML patients. In contrast, dyserythropoietic changes had a similar incidence in both groups. When compared with the clinical features at initial diagnosis in AML cases, the dysmegakaryocytic changes in remission marrow were found to be significantly more frequent in patients with monocytic involvement (mainly M4) or trilineage myelodysplasia (T-MDS AML). Disease-free survival was significantly shorter in patients with micromegakaryocytes (P less than 0.05) or neutrophils with hypogsegmented nuclei (P less than 0.05) than in those without these features. Overall survival was also significantly shorter in patients with micromegakaryocytes (P less than 0.05). These findings may help in developing new strategies for the post-remission therapy of AML, and also suggest that myelodysplastic changes in the remission marrow of de novo AML patients may be related to haematopoietic recovery by a preleukaemic clone which eventually leads to early leukaemic relapse. Dysplastic marrow, however, was not necessarily associated with peripheral pancytopenia in the present series, warranting basic research on such putative clonal remissions.