ACUTE MYELOID-LEUKEMIA WITH T(6-9) (P23-Q34) - ASSOCIATION WITH MYELODYSPLASIA, BASOPHILIA, AND INITIAL CD34 NEGATIVE IMMUNOPHENOTYPE

The translocation (6;9)(p23;q34) is a rare cytogenetic aberration foun d in patients with acute myeloid leukemia (AML). The clinical, morphol ogic, and immunophenotypic findings of eight t(6;9) acute leukemias ar e described. The patients included six men and two women with a mean a ge of 38.5 years. The leukemias were classified in the French-American -British (FAB) system as AML FAB M2 in four cases and as FAB M4 in fou r cases. Underlying myelodysplasia was evident in six cases. Bone marr ow basophilia was found at presentation in six of the seven cases stud ied. In two cases with basophilia, darkly stained granules were also p resent in many eosinophils. In one case, initial basophilia was absent , but was present at relapse, as were eosinophils containing darkly st ained granules. Iron stains were available in five cases; four showed increased incorporation and three had ringed sideroblasts. All cases s tudied by flow cytometry (six at presentation and three at relapse) ex pressed CD13, CD33, and human leukocyte antigen-DR. At presentation, f ive cases were CD34 negative. In one case at presentation, a subset of blasts (18%) weakly expressed CD34. Three cases studied at relapse we re positive for CD34. Two of seven cases studied were terminal deoxynu cleotidyl transferase positive. The t(6;9)(p23;q34) was the only cytog enetic abnormality in five cases. Trisomy 8 was found in two cases, an d ring 12 was present in one case. Three patients are living with refr actory leukemia 6 weeks to 6 months after initial diagnosis, and three patients died of complications of allogeneic bone marrow transplantat ion. Only one patient is alive without evidence of disease 3 years aft er bone marrow transplantation. t(6;9) leukemia is an unusual type of AML that is associated with poor prognosis, early age of onset, basoph ilia, myelodysplasia with frequent ringed sideroblasts, and a CD34-neg ative initial phenotype.