title: Evidence for clonal evolution in pre-B-cell leukaemia.
abstract: This case study provides evidence for clonal evolution in pre-B-cell leukaemia. At diagnosis, the lymphoblasts from a 3-year-old boy were morphologically subtyped as L1 (French-American-British classification). Their immunophenotype was CALLA+, CIgM+, SIg-, TdT+, and the karyotype was pseudodiploid with a 1;19 translocation. Striking shifts were apparent when the child relapsed 16 months later. The morphologic subtype had changed to L3, CALLA and TdT had disappeared, and a consistent karyotype was lacking. The modal chromosome number had increased through clonal evolution to 85, the 1;19 translocation was retained, and a new marker, a 14q+ (partial duplication) appeared and was present in a majority of cells. These cytogenetic findings are characteristic of a transforming state. However, despite the loss of TdT, the appearance of classic L3 morphology and the acquisition of a 14q+ marker, the cells retained a predominantly pre-B phenotype.
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis; D001402:B-Lymphocytes; D001853:Bone Marrow / Q000473:pathology; D002675:Child, Preschool; D002869:Chromosome Aberrations; D006801:Humans; D007621:Karyotyping; D007945:Leukemia, Lymphoid / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D008297:Male
chemical_list: D000951:Antigens, Neoplasm; D000954:Antigens, Surface