CHILDHOOD B-CELL ACUTE LYMPHOBLASTIC-LEUKEMIA WITH FAB-L1 MORPHOLOGY AND A T(9-11) TRANSLOCATION INVOLVING THE MLL GENE

The t(9;11)(p21-22;q23) translocation is frequently associated with ac ute monoblastic leukemia but may occasionally be seen in patients with acute lymphoblastic leukemia (ALL). We report a case of childhood ALL associated with t(9;11)(p21-22;q23) as the unique recurring chromosom al abnormality. A 3-month-old girl presented with ''lymphomatous'' ALL (renal enlargement), a high leukocyte count and central nervous syste m (CNS) involvement. Leukemic cell typing revealed a sIg+ B-cell immun ophenotype without CD10 and CD34 antigenic expression while the blast cell morphology was of the FAB-L1 type. Splitting of a YAC encompassin g the MLL gene was shown by fluorescence in situ hybridization (FISH) studies of the patient's metaphase chromosomes. Rearrangement of the M LL gene was confirmed by Southern blot analysis. Despite treatment wit h an hyperintensive polychemotherapeutic regimen, the patient achieved a complete remission but relapsed 9 months later. These results provi de further evidence that the t(9;11) may be observed in ALL, involves the MLL gene and is associated with a poor outcome. Moreover, this obs ervation clearly illustrates that sIg+ B-cell ALL is not necessarily a ssociated with a Burkitt (L3) morphology.