Morphologically identified myeloblasts were relocated on the smear after FISH and were found to be PML/RARA positive in 91%, abnormal promyelocytes in 97%.     ///    HLA-DR-positive cells contained a PML/RARA rearrangement in 24% of cells in one case and were negative in the two other cases investigated.     ///    "Erythroblasts, lymphocytes and plasma cells did not show a PML/RARA rearrangement. "    ///    "Accordingly, all cells expressing CD3 or CD19 were PML/RARA negative. "    ///    CD34 positive precursor cells identified by FICTION were PML/RARA positive in 97%.     ///    The low proportion of PML/RARA-positive PMN points to the impairment of blast cell differentiation beyond the promyelocyte stage but also emphasizes the existence of normal residual haemopoietic stem cells from which PML/RARA-negative PMN must be derived.. 