A De Novo Childhood Case of T-cell Lymphoblastic Leukemia with High Hyperdiploid Karyotype Carrying an Unreported Balanced Translocation t(X;5)(q26;q31.3~32) in A Male Patient

(1) Background: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy of thymocytes with multiple genetic abnormalities, accounting for 15% and 25% of newly diagnosed cases of ALL in children and adults, respectively. Notably, T-ALL has a 3-fold higher incidence in males. Cytogenetically detectable structural or numerical chromosomal abnormalities are detected in ~50% of ALL cases. Such aberrations have a prognostic significance. High hyperdiploidy (51–65 chromosomes, HeH) is an established genetic subtype of B-cell ALL (B-ALL), which is associated with good survival and an excellent outcome. Furthermore, the most commonly acquired chromosomes in HeH are +4, +6, +10, +14, +17, +18, +21 and +X. However, the mechanism for chromosomal gains in ALL and their role in leukemogenesis are still ambiguous. (2) Methods: Banding cytogenetics, and molecular cytogenetics using whole chromosome paints and array-proven multicolor banding (aMCB) were used on chromosomal preparations together with immunophenotyping of the bone marrow cells. (3) Results: A HeH karyotype including a balanced translocation t(X;5) was detected in an, according to World Health Organization (WHO) classification, de novo childhood cortical-T-ALL case. (4) Conclusions: To the best of our knowledge, a childhood T-ALL case associated with a HeH karyotype was not previously reported. Even though an involvement of cytoband Xq26 in a rearrangement has already been observed, here a rearrangement involving Xq26 in a male ALL case was seen for the first time, suggesting a gender association, but not limitation of this cytogenetic ALL subgroup.