title: Near-haploid common acute lymphoblastic leukaemia of childhood with a second hyperdiploid line: a DNA ploidy and fluorescence in-situ hybridization study.
abstract: Near-haploidy is a rare cytogenetic finding in childhood acute lymphoblastic leukaemia (ALL) and is associated with a poor prognosis. A second hyperdiploid line, occurring presumably by endoreduplication of the near-haploid stemline, is often observed. We present a case of common ALL in relapse characterized morphologically by a dual population of small and large lymphoblasts. Cytogenetic analysis supplemented with fluorescence in-situ hybridization (FISH) studies localized near-haploidy and hyperdiploidy to the small and large blast population respectively. DNA ploidy determination confirmed two abnormal clones with near-haploidy as the predominant one. A novel t(9;12)(q11;q13) was present in the near-haploid clone and was duplicated in the hyperdiploid clone. This finding identified cells bearing near-haploidy to be the clonogenic population following malignant transformation and confirmed endoreduplication as the mechanism for the presence of associated hyperdiploidy.
authors.affiliation: Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong.
authors.forename: S K
authors.initials: SK
authors.lastname: Ma
authors.forename: G C
authors.initials: GC
authors.lastname: Chan
authors.forename: T S
authors.initials: TS
authors.lastname: Wan
authors.forename: C K
authors.initials: CK
authors.lastname: Lam
authors.forename: S Y
authors.initials: SY
authors.lastname: Ha
authors.forename: Y L
authors.initials: YL
authors.lastname: Lau
authors.forename: L C
authors.initials: LC
authors.lastname: Chan
mesh_terms: D002648:Child; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D002999:Clone Cells; D004273:DNA, Neoplasm / Q000235:genetics*; D004171:Diploidy; D005260:Female; D006238:Haploidy; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D014178:Translocation, Genetic
chemical_list: D004273:DNA, Neoplasm