Near-haploid B lymphoblastic leukemia with an apparent hyperdiploid karyotype: The critical role of SNP analysis in establishing proper diagnosis

Abstract

Molecular genetic analysis is indispensible in both classification and prognostication of hematopoietic malignancies. The evolution of genetic analysis from conventional cytogenetics to novel genomic technologies has increased our ability to detect subtle and nonconventional mutations in leukemia and lymphoma. Near haploidy, a subtype of hypodiploidy, is a rare entity that carries a particularly poor prognosis in B lymphoblastic leukemia (B-ALL). Near-haploid B-ALL usually quickly evolves by doubling of the chromosome number, creating confusion with the prognostically favorable hyperdiploid B-ALL subtype. Here, we describe a case of B-ALL in which single-nucleotide polymorphism (SNP) microarray analysis was used to identify a hyperdiploid clone that had evolved from a presumptive, near-haploid clone. By conventional methods, this clone may have been easily misinterpreted as a common hyperdiploid clone. Given the extreme prognostic differences of the two clones, this distinction is especially critical to accurately guide therapy. In this case report and brief review, we discuss the role of SNP microarray analysis in the diagnosis and proper subclassification of B-ALL as well as its potential in the identification of genetic therapeutic targets. © 2013 Springer-Verlag Berlin Heidelberg.