REFRACTORY-ANEMIA WITH PRELEUKAEMIC POLYCLONAL HEMATOPOIESIS AND THE EMERGENCE OF MONOCLONAL ERYTHROPOIESIS ON DISEASE PROGRESSION

We describe a young woman with a myelodysplastic syndrome (MDS) of the type refractory anaemia (RA) which remained stable for 11 years and then underwent rapid progression manifested by bone marrow failure with the emergence of a complex clonal cytogenetic abnormality, Peripheral blood granulocytes, mononuclear cells and bone marrow erythroblasts were all polyclonal by X-inactivation analysis detected by the probe M27B during the preleukaemic phase, On disease progression, bone marrow erythroblasts developed an extremely skewed monoclonal pattern of X-inactivation. In some cases of MDS, therefore, polyclonal haemopoiesis can be detected for a considerable time during the preleukaemic phase and we report the demonstration of bone marrow erythroblasts changing from a polyclonal to a monoclonal pattern on disease progression.