Dysmyélopoïèse et syndromes myélodysplasiques : description - démarche diagnostique

Myelodysplasia is characterized by morphological qualitative abnormalities in one or more of the myeloid (erythroid, granulocytic and megakaryocytic) cell lines. It is a major criterion for the diagnosis of myelodysplastic syndromes but it can be observed, often as reversible symptom, in other disorders or in various clinical conditions. Myelodysplasia may be detected on peripheral blood smear. Bone marrow aspirates are required to analyze qualitative abnormalities of myeloid precursors, to evaluate the percent of blasts and to assess the presence of ring sideroblasts (Prussian blue reaction). For most patients, it is possible to diagnose the myelodysplastic syndrome on the basis of the previous morphological data. In some cases, cytological data are insufficient to confirm the myelodysplastic syndrome. Additional tests can be applied and may help in reaching the conclusion. When those investigations remain negative and after exclusion of other disorders, persistent cytopenias should be viewed as the recently described “idiopathic cytopenia of undetermined significance” (ICUS) and the patient's hematologic and cytogenetic status should be carefully monitored to detect a possible myelodysplastic syndrome in the follow-up.