Myelodysplastic syndrome or acute myeloid leukemia? A study of 28 cases presenting with borderline features.

Some patients present borderline features between acute myeloid leukemia (AML) and typical myelodysplastic syndromes (MDS): an excess of blasts insufficient to conclusively diagnose AML, yet above the figures usually compatible with MDS or the presence of Auer rods associated with a moderate excess of blasts. This presents considerable difficulties in diagnosis and management. The authors studied 28 such cases using the French-American-British Co-operative Group (FAB) classification, which groups them into a separate category termed "refractory anemia with excess of blasts in transformation" (RAEB-T). This was found to be a heterogenous group. Certain patients (4/28) had a previously established myelodysplasia, but most presented directly as RAEB-T. Two very different pictures emerged: a few patients (4/28) were young, with presentation and evolution similar to classic AML, for whom combination chemotherapy was effective; the majority (20/28) were older, with more varied clinical and cytologic presentation, for whom chemotherapy was of little effect and who presented a picture resembling classic RAEB with a median survival of 10 months.