We describe the case of a 16 year-old female with mixed phenotype acute leukemia B/myeloid, NOS (formerly biphenotypic leukemia) with masked hypodiploidy and somatic TP53 and CDKN2A/B deletions. She achieved morphologic remission with lymphoid-directed multi-agent chemotherapy, but experienced an early medullary relapse 11 months from initial diagnosis. Her case details the unusual finding of h...

An 18-month-old girl was diagnosed with pre-pre-B ALL/t(4;11) leukemia, which during the treatment and after matched bone marrow transplantation (BMT), underwent two consecutive switches from lymphoid to myeloid lineage and vice versa. The high expression of HOXA9 and FLT3 genes remaining genotypically stable in a leukemia throughout phenotypic switches, suggests that this leukemia may have ori...

The laboratory characterization of acute leukemia has evolved as new technologies have emerged and been applied in the routine evaluation of these hematologic malignancies. With the use of morphology, cytochemistry, flow cytometry, cytogenetics, and molecular genetics, it is possible to characterize acute leukemias in an extremely sophisticated and (ideally) therapeutically rational manner. Suc...

Congenital leukemia is rarely encountered in clinical practice, even in tertiary children's hospitals. Leukemia may cause significant coagulopathy, putting the patient at risk of intracranial hemorrhage. In this case, the authors present a female infant with a unique mixed phenotypic congenital acute myeloid leukemia showing mixed-lineage leukemia (MLL) rearrangement and severe coagulopathy res...

1. Reiter A, Schrappe M, Luwdig WD, et al. Chemotherapy in 998 unselected childhood acute lymphoblastic leukemia patients. Results and conclusions of the multicenter trial ALL-BFM 86. Blood 1994; 84:3122-33. 2. Wan JH, Trainor KJ, Brisco MJ, Morley AA. Monoclonality in B-cell lymphoma detected in paraffin wax embedded using the polymerase chain reaction. J Clin Pathol 1990; 43:888-90. 3. Brisco...

The TEL-JAK2 gene fusion, which has been identified in human leukemia, encodes a chimeric protein endowed with constitutive tyrosine kinase activity. TEL-JAK2 transgenic expression in the mouse lymphoid lineage results in fatal and rapid T-cell leukemia/lymphoma. In the present report we show that T-cell leukemic cells from EmuSRalpha-TEL-JAK2 transgenic mice present an aberrant CD8(+) differen...

Extensive immunologic surface marker analyses and binding competition assays demonstrated that B43 monoclonal antibody (MoAb) is a new member of the CD19 cluster that recognizes the same surface epitope as several other anti-CD19 MoAbs. We used B43 MoAb to test for CD19 expression on neoplastic cells from 340 leukemia and 151 malignant lymphoma patients and on nonneoplastic cells in normal lymp...

TO THE EDITOR: Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is characterized by the specific immunophenotype of CD1a, CD8, and CD5 with stem cell or myeloid marker expression. This leukemia presents a particular flow cytometric diagnostic challenge, as it frequently exhibits sufficient myeloid-lineage differentiation to be classified as mixed-phenotype acute leukemia (MPAL). Th...

Our understanding of leukemia development and progression has been hampered by the lack of in vivo models in which disease is initiated from primary human hematopoietic cells. We showed that upon transplantation into immunodeficient mice, primitive human hematopoietic cells expressing a mixed-lineage leukemia (MLL) fusion gene generated myeloid or lymphoid acute leukemias, with features that re...

The aim of the multicentric trial LALA87 was to test the efficacy of different postremission therapies in adults (15 to 60 year olds) with acute lymphoblastic leukemia (ALL). An immunologic subclassification based on surface marker expression was proposed. Among the 562 tested patients, 51 1 were assigned either to the B lineage (361 cases, 6 3 % ) or to the T lineage (150 cases, 26%). T-ALL we...