Advanced pediatric myelodysplastic syndromes: can immunophenotypic characterization of blast cells be a diagnostic and prognostic tool?

BACKGROUND: The diagnosis of myelodysplastic syndromes (MDS) is mainly based on morphology and cytogenetic analysis. Several efforts to analyze MDS by flow cytometry have been reported in adults. These studies have focused on the identification of abnormalities in the maturation pathway of antigen expression of myelo-monocytic cells, and characterization of blast populations. Therefore, phenotype has been proposed as a diagnostic and prognostic criterion tool for adult MDS. The current article provides data concerning the blast phenotype in pediatric MDS. PROCEDURE: We evaluated by multiparameter flow cytometry 26 MDS pediatric patients with more than 2% of blast cells at bone marrow morphological examination (17 de novo MDS and 9 secondary MDS) and 145 pediatric de novo acute myeloid leukemia (AML) cases (M3 excluded). As control group, 12 healthy age-matched donors for allogenic bone marrow transplantation (BMD) and 6 regenerating bone marrow samples, collected from children with acute lymphoblastic leukemia (ALL) in remission after induction chemotherapy, were studied. RESULTS: We identified a blast immunophenotype typically expressed in most MDS cases and a strong correlation between CD7 expression and poor outcome. CD34+ compartment in MDS bone marrow was also analyzed: a significant decrease of B-cell precursors was detected in MDS patients independent of age. CONCLUSIONS: Our data suggest that the blasts phenotypic features can constitute a diagnostic and prognostic tool also for pediatric MDS.