Infantile acute leukemia with 11q23 chromosome abnormality and lineage infidelity

An infant case of acute leukemia (AL) showed lineage infidelity and a chromosome rearrangement involving 11q23. This case was morphologically diagnosed as ALL-L2 according to the FAB classification. However, the blast cells were highly positive for monoclonal antimyeloid antigens (Mol and TG-8) and lymphoid markers (B1, J5 and TdT). These immunologic findings indicated that the blast cells had characteristics of lymphoid B-cell and myeloid lines. In the literature, so-called "11q23 chromosome abnormalities," commonly observed in acute nonlymphoblastic leukemia (ANLL) and in a subtype of acute lymphoblastic leukemia (ALL) with t(4;11) were observed in both lymphoid and myeloid acute leukemias, with some of them recently reported to have lineage infidelity. These unique characteristics may indicate the possibility that the latter is a variation of the former, and support the hypothesis that the chromosomal rearrangement at 11q23 occurs at a multipotent stem-cell level.