Myelodysplastic syndromes: analysis of 131 cases according to the FAB classification

The clinical and haematological findings in 131 patients with myelodysplastic syndromes (MDS), none of which had previously received chemotherapy or radiotherapy, classified according to the FAB criteria, were analysed. The distribution among the 5 subgroups was: RA 31 patients, RAS 19, RAEB 23, CMML 29 and RAEBT 29 patients. There were difficulties in the classification of 24 patients. These included, first, 8 cases with myeloid hyperplasia of the bone marrow (BM) but without monocytosis or excess of blasts of the BM. They were classified as RA. Second, 8 cases with sideroblastosis but with monocytosis or excess of blasts of the BM were classified 3 as RAEB, 2 as CMML and 3 as RAEBT. Finally, 8 cases with absolute monocytosis and BM blasts 15-30% were classified as CMML. 37 of 82 dead patients (45.1%) had transformed to acute non-lymphoblastic leukaemia (ANLL). The incidence of evolution to ANLL was low for RA and RAS (6.30% and 12.5% respectively), while it was 37.5% for RAEB, 57.1% for CMML and 77.2% for RAEBT. The median survival for each subgroup was: RA 18 months; RAS 25; RAEB 13; CMML 14 and RAEBT 10 months. It is concluded that the FAB classification with some modifications recognises group of MDS with different prognosis.