The cells are ambiguous, not the message

In this issue of Blood , Hrusak et al show the superiority of acute lymphoblastic leukemia (ALL) type therapy in most cases of ambiguous lineage acute lymphoblastic leukemia (ALAL) in childhood. 1 ALL cells commonly express either B-cell antigens (∼75% of cases) or T-cell antigens (20% of cases). In ∼4% of cases, the leukemic cells coexpress B and myeloid antigens, or, more rarely, T plus myeloid antigens, or, extremely rarely, are trilineage positive. In a few cases, no lymphoid lineage-specific antigens are expressed. The cells appear on fluorescence-activated cell sorter staining as a single population in 75% of cases or as bilineal.