Four Cases of t(4;11) Acute Leukemia and Its Myelomonocytic Nature in Infants

Four cases of acute infantile leukemia with translocation (4;11) (q21;q23) are reported. Although leukemia with this chromosomal abnormality has been classified as L2 acute lymphoblastic leukemia by the FAB classification, two of our cases appeared to be of myelomonocyte origin as demonstrated by cytochemical, immunologic, and electron microscopic studies and differentiation induction by 12-tetradecanoyl-phorbol-13-acetate and methylformamide. This chromosomal change is associated with poor prognosis.