A B-ALL Pediatric Patient with a Cryptic IGH Rearrangement Within the Context of a Complex Karyotype

B-cell acute lymphoblastic leukemia (B-ALL) can afflict both adult and pediatric patients and is characterized by a build-up of B lymphoblasts. Here we present a case of a 25-year-old male patient with a history of B-ALL. Ninety percent of the bone marrow revealed pancytopenia with sheets of B lymphoblasts consistent with the diagnosis of B-ALL for acute pre-B lymphoblastic leukemia. The immunophenotype also presented predominant immature precursor B lymphoid cells positive for CD19, CD10, CD34, CD58, CD38, CD9, and TdT. Chromosome analysis of the bone marrow showed a complex karyotype described as 45~47,XY,i(8)(q10),der(10)add(10)(p11.1)add(10)(q23),-20,+1~2mar[cp3]/46,XY[36]. While IGH rearrangements were cryptic cytogenetically, DNA FISH analysis showed evidence of the IGH (14q32.2) gene rearrangement in 96.5% of the nuclei examined. These results were described as nuc ish(IGHx2)(5'IGH sep 3'IGHx1)[187/200],(5'IGH,3'IGH)x1~4(5'IGH con 3'IGHx0~2) [6/200]. The remaining probes were normal. Further studies using the MYC/IGH DC, DF probe from Abbott showed a gain of IGH signal in 7.5% of the nuclei examined: nuc ish(MYCx2,IGHx3)[15/200]. Metaphase FISH also showed that what appeared to be an isochromosome 8q was a derivative chromosome 8 defined as add(8)(p11.2) that contained a green IGH signal. In light of these results the karyotype was characterized as 45~47,XY,add(8)(p11.2),der(10)add(10)(p11.1)add(10)(q23),-20,+1~2mar[cp3].ish add(8) (p11.2) IgH+. IgH abnormalities are rare in B-ALL and are usually associated with a poor prognosis. However, at the present time our patient presented no evidence of persistent or residual disease and a cytogenetic response to the present therapy.