[Clinical and cytological features of CD7 positive biphenotypic leukemias]

Clinical and cytological features of CD7 positive acute leukemias with biphenotypic characteristics in childhood were documented. From 87 patients with CD7+ acute leukemias, nine patients were selected on the basis of the biphenotypic expression of T-lymphoid and myelomonocytic antigens. The blasts of these patients expressed cell surface CD7, cytoplasmic CD3 and cytoplasmic CD13. In addition to these antigens, surface CD13 was also expressed after short term culture without any mitogens or stimulators. The double PAP method for detecting cytoplasmic antigens (CD3, CD13, beta F1, delta TCS1) was employed in this study. The average age of these patients was higher (10.2 y/o) than patients with common ALL. Mediastinal masses were observed in 4 of 9 patients. They were treated according to the diagnoses based on conventional hematological methods and surface antigen expression. In all 9 patients, complete remission was achieved, however, early relapse was noticed in 7. This study suggests that the leukemia cells of these patients may be derived at an early stage during the differentiation of multipotential hematopoietic stem cells. New therapeutic approaches are necessary to improve the outcome of such T/M biphenotypic leukemias.