Abstract

We present a pediatric case of acute lymphoblastic leukemia (ALL) with chromosomal translocation 1;19 lacking E2A-PBX1 chimeric transcripts. On admission, the patient showed remarkable splenomegaly. Laboratory findings demonstrated that WBC was 12900/microl with blasts 61.5%. Bone marrow examination revealed 1282 X 10(3)/microl of the nucleated cell count with 95.5% lymphoblasts. Surface marker analysis showed an early pre-B lineage immunophenotype (CD10+, CD19+, CD34+, surface Ig-). Although G-banding chromosomal analysis showed 46,XY,der(19)t(1;19)(q23;p13), E2A-PBX1 chimeric transcripts and E2A gene rearrangement were not detected with the polymerase chain reaction method and Southern blot analysis, respectively. The patient was assigned to high-risk ALL according to the criteria of the Japan Association of Childhood Leukemia Study. His clinical response to prednisolone monotherapy for the initial 7 days and subsequent multidrug chemotherapy was excellent, and he achieved complete remission on day 15, which has lasted for more than 30 months. We reviewed the bibliography of the clinical and biological features of 17 children with t(1;19)+E2A-PBX1- ALL including this case. The two prominent characteristics included an early pre-B immunophenotype (11/13) and hyperdiploid (>50 chromosomes) chromosome abnormality (8/14). However, there was substantial heterogeneity in the demographic features and prognosis. Further accumulation of such patients will facilitate the determination of the appropriate treatment for childhood t(1;19)+E2A-PBX1- ALL.