Diagnosis, classification, and cytogenetics of myelodysplastic syndromes

The diagnosis of myelodysplastic syndromes (MDS) is essentially morphological and based on the presence of dysplastic features in the peripheral blood and bone marrow. The French-American-British (FAB) Cooperative Group proposed a classification based on easily obtainable laboratory information. In spite of some limitations, the FAB criteria have been useful for a long time. Currently, the recognition of other distinct morphological MDS subgroups such as hypocellular MDS and MDS with myelofibrosis, the increasing incidence of MDS in children as well as that of therapy-related MDS, and the finding of specific chromosomal alterations associated with different morphological features, reveal the insufficiency of this classification. The aim of the present review is to examine some new aspects of the diagnosis, classification, and cytogenetics of MDS.

The authors of this review have been actively working and contributing original papers on MDS for the last 15 years. They also organized or participated in the Fourth International Symposium on MDS (Barcelona, April 24-27, 1997). In addition, the present review critically examines relevant articles and abstracts published in journals covered by the Science Citation Index and Medline.

Most of investigators working on MDS tend to integrate morphology and cytogenetics in the diagnosis and classification of these disorders. FAB criteria remain useful particularly for patients with not available cytogenetic study. Refractory cytopenia with multilineage dysplasia should be considered as a new MDS subtype. Some authors propose considering all patients with more than 20% of blast cells in peripheral blood or bone marrow as having acute leukemia. Chronic myelomonocytic leukemia with myeloproliferative features may be included among chronic myeloproliferative disorders. MDS with myelofibrosis is recognized as a new MDS subtype. Therapy-related MDS (t-MDS) should be classified according to the involved agents. Finally, besides including chromosomal abnormalities in the diagnosis (e.g., RAEB with trisomy 8), several cytogenetic abnormalities such as deletion 5q and deletion 17q, associated to specific clinical-morphological features, should be of help to identify new MDS syndromes.