Classification Investigation Of Myelodysplastic Syndrome

Myelodysplastic syndromes (MDS) are clonal hematologic stem cell disorders characterized by ineffective hematopoiesis. These diseases were initially named by the French-American-British (FAB) group in 1976. In 1982, this same study group proposed a classification based on morphologic features in blood and bone marrow, namely medullary and peripheral blast cell count, number of monocytes in peripheral blood. Five subgroups were established: refractory anemia (RA), RA with ringed sideroblasts (RAS), RA with excess of blasts (RAEB), RAEB in transformation (RAEB-t), and chronic myelomonocytic leukemia (CMML). In 1985, FAB group proposed the concept of nonerythroid cells (NEC) count. They recommended that only nonerythroid cells should be considered in the differential counts aimed at classifying acute myeloid leukemia and myelodysplastic syndrome, that is, exclude from the differential count plasma cells, lymphocytes, mast cells, macrophages and all nucleated erythroid precursors. For nearly 2 decades this classification served as the standard for the evaluation of MDS, but many questions were found during the practical uses. In 1999, the World Health Organization (WHO) published a revised classification of MDS. The definitions of RA and RARS became more consistent and included the presence of dysplastic features in the erythroid lineage only. At the moment RAEB remains unchanged, though some investigators suggest further discrimination into RAEB I with 5% to 10% and into RAEB II with 11% to 20% blasts in the bone marrow. Three new subgroups were incorporated: (1) refractory cytopenia with multilineage dysplasia (RCMD), which is equivalent to RA or RARS in the FAB classification with the presence of dysplastic features in 2 or 3 cell lineages; (2) del (5q) syndrome, characterized by dysplastic features in the erythroid lineage only and deletion of the long arm of chromosome 5 and (3) MDS unclassifiable (MDS unclass). Two other FAB subgroups RAEB-t and CMML have been excluded from the new MDS classification. Nonerythroid cells count adopted by our morphologic laboratory and hematology laboratory of Beijing and Shanghai is only excluding the erythroblasts from the count. This does not accord with the FAB concept. In this study, we provide a change of MDS classifications by using nonerythroid cells count proposed by FAB group and recalculating the proportion of blast cells from 108 patients with MDS who were diagnosed at our department between January, 2000 and April, 2005. The result is as follow. In 108 patients, classifications of 22 patients have changed. In 41 patients who were diagnosed as RAEB, classifications of 12 patients have changed and they should be diagnosed as AML. In 62 patients who were diagnosed as RA, classifications of 10 patients should be diagnosed as RAEB. Using different nonerythroid cells count have a drastic effect on the classification. Classification correlates with the choice of treatment project and prognosis of MDS. So, whether we should adopt nonerythroid cells count proposed by FAB group deserves investigation. Of these 108 patients, 45 patients have karyotype analysis. To compare the results of peripheral hypocytosis,the detection rates of karyotype abnormality and IPSS risk grouping of myelodysplastic syndromes classified by FAB or WHO classification ,45 patients are reclassified with WHO classification. The results are...