Acute Myeloid Leukemia Expressing T-Cell Antigens: Clinico-Hematological Report on Six Cases

In a series of 107 patients suffering from acute myeloid leukemia (AML), blast cells from six patients were found to simultaneously express CD2 and CD7 antigens along with CD13, CD33, and CDw 65 in various combinations. The frequency of the expression of both lymphoid markers recurred with a higher incidence than that anticipated by multiplying single antigens frequency. The clinical and hematologic features from CD2+/CD7 + AML patients were studied as well as compared with those of CD2-/CD7- AML patients observed in the same period. Morphologically, bone marrow smears from the AML hybrid subset showed a preponderant population of agranular blasts along with a minority of typical myeloid cells, characterized by larger amount of cytoplasm and, in three cases, by rare but distinct Auer Rods. In all cases more than 3% of blast cells were positive for myeloperoxidases and all samples were classified as M1 according to FAB classification. Clinically, CD2 + /CD7 + patients presented with a higher incidence of adenopathy and meningeal leukemia than did patients with CD2 + /CD7 - AML and were characterized by poor response to therapy in terms of both achievement and duration of remission. We conclude that simultaneous expression of CD2 and CD7 in AML is a non random event, recurring in more than 5% of cases and is associated with distinct clinical and hematologic features.