PRESENCE OF T(8-21)(Q22-Q22) IN MYELOPEROXIDASE-POSITIVE, MYELOID SURFACE ANTIGEN-NEGATIVE ACUTE MYELOID-LEUKEMIA

Although acute myeloid leukemias (AMLs) cytochemically negative for my eloperoxidase are now well recognized, myeloid surface antigen-negativ e AMLs are rare. The morphologic, cytochemical, immunologic, and cytog enetic or molecular features of such cases are described in four adult s aged 19 to 60 years. All had AML with maturation (FAB M2) and were m yeloperoxidase positive. Immunologic studies showed all to be HLA-DR p ositive but negative for the CD13, CD14, and CD33 antigens. Two of fou r were CD34 antigen positive. Cytogenetic studies were performed in th ree patients, and all demonstrated t(8;21)(q22;q22). In studies using the reverse transcriptase polymerase chain reaction in two patients, i ncluding the patient in whom karyotypic analysis was not performed, th e AML1-ETO fusion product of t(8;21) was identified. These findings su ggest an association between the lack of myeloid antigen expression in myeloperoxidase-positive AML and the presence of t(8;21). In addition , the results demonstrate the continued need for cytochemical studies in the evaluation of acute leukemias.