DISCREPANT CYTOGENETIC AND FLUORESCENCE IN-SITU HYBRIDIZATION RESULTSIN A 26-YEAR-OLD MALE WITH EARLY T-CELL ACUTE LYMPHOCYTIC-LEUKEMIA

Analyzable G-banded metaphases were normal in bone marrow from a 26-ye ar-old male having 80% blasts. Fluorescence in situ hybridization (FIS H) using the centromeric probe, D7Z1, revealed 85% of interphase cells with one signal for chromosome 7. Chromosome painting revealed a chro mosome 7 rearrangement in a few metaphases that were otherwise unanaly zable. A repeat bone marrow confirmed 3 of 20 metaphases, by G-banding , to have multiple rearrangements and aneuploidy, including a large de rivative chromosome involving a complex rearrangement of chromosomes 5 , 7, and 9; that is, der(5)t(5;9)(q31;q13)ins(5;7)(p15;q?31q?34), with loss of most of chromosome 7 (7 pter-->7q?31); one normal 7 was prese nt. Immunophenotyping characterized the patient's condition as an earl y T-cell acute lymphocytic leukemia (ALL), with a population of cells suggesting biphenotypic leukemia. He attained a complete clinical remi ssion with chemotherapy. Six months after the initial presentation he received an allogeneic bone marrow transplant. Three months later a CN S relapse was followed by a bone marrow relapse. At this time, eight m onths after transplant, repeat study of his bone marrow revealed the m ajority of metaphases had structural and numerical chromosome abnormal ities similar to the small clone in the earlier study, including der(5 )t(5;9)ins(5;7), but with two normal 7s. FISH showed two 7-centromere signals in interphase. The patient expired one month later. (C) Elsevi er Science Inc., 1998.