Near-haploid common acute lymphoblastic leukaemia of childhood with a second hyperdiploid line: a DNA ploidy and fluorescence in-situ hybridization study.
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.
Ma
S K
SK
Department of Pathology, University of Hong Kong, Queen Mary Hospital, Hong Kong.
Chan
G C
GC
Wan
T S
TS
Lam
C K
CK
Ha
S Y
SY
Lau
Y L
YL
Chan
L C
LC
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
D004273:DNA, Neoplasm