Submitted July 2, 2007
Accepted October 10, 2007
Identification of distinct prognostic subgroups in low and intermediate-1 risk myelodysplastic syndromes by flow cytometry
Arjan A van de Loosdrecht*, Theresia M Westers, August H Westra, Angelika M Drager, Vincent HJ van der Velden, and Gert J Ossenkoppele
Department of Hematology, VU University Medical Center, VU-Institute for Cancer & Immunology, Amsterdam, Netherlands
Department of Immunology, Erasmus Medical Center, Rotterdam, Netherlands
* Corresponding author; email: a.vandeloosdrecht{at}vumc.nl.
The WHO classification contributes to refined classification and prognostication of myelodysplastic syndromes (MDS). Flow cytometry might add significantly to diagnostic and prognostic criteria. Our analysis of bone marrow samples from 50 MDS patients showed aberrant expression of differentiation antigens in the myelomonocytic lineage. This also accounted for RA±RS indicating multilineage dysplasia. Aberrancies in granulopoiesis or monocytopoiesis were observed in 92% of the cases and monocytopenia in 40%. In 38% of cases, CD34+ myeloid blasts expressed CD5, CD7 or CD56. Flow cytometry data were translated into a numerical MDS flow-score. Flow-scores increased significantly from RA±RS, RCMD±RS up to RAEB-1 and RAEB-2. No significant differences were observed between WHO-cytogenetic subgroups. Flow-scores were highly heterogeneous within IPSS subgroups. Patients in progression to advanced MDS or acute myeloid leukemia had a significantly higher flow-score compared to non-transfusion-dependent patients. In 60% of patients with transfusion-dependency or progressive disease, myeloid blasts expressed CD7 or CD56 in contrast to only 9% of non-transfusion-dependent patients. Moreover, all pure RA±RS patients with aberrant myeloid blasts showed an adverse clinical course. In conclusion, flow cytometry in MDS identified aberrancies in the myelomonocytic lineage not otherwise determined by cytomorphology. Additionally, flow cytometry identified patients at risk for transfusion dependency and/or progressive disease independent of known risk groups, which might have impact on treatment decisions and prognostic scoring system in the near future.
