Hypodiploidy in a pediatric patient of T-cell acute lymphoblastic leukemia: a case report.

T-cell acute lymphoblastic leukemia is a subtype of acute lymphoblastic leukemia, one of the most common childhood neoplasms. Hypodiploidy is a chromosome abnormality with fewer than 45 chromosomes and is associated with unsatisfactory clinical outcomes in acute lymphoblastic leukemia. We report clinical and genetic findings of a 14-year-old male with T-cell acute lymphoblastic leukemia with low-hypodiploidy. The medical history included neck pain for a month, facial nerve palsy on the right side for 6 days, fever, drowsiness, and weakness for 3 days, vomiting, diarrhea for 1 day. The physical examination presented features of hypovolemia, palsy of the facial nerve on the right side, enlarged lymph nodes, hepatosplenomegaly, sore throat, and petechiae of the skin. Radiological images indicated lesions of different organs. Bone marrow biopsy confirmed precursor T-ALL. In the FISH tests, KMT2A and BCR/ABL1 rearrangements were not observed. GTG banding revealed 3 cell clones, which confirmed the hypodiploidy. Multiplex RT-qPCR was performed. STIL/TAL1 (del1p32) gene rearrangement was found in the blast cells. Additional tests were performed using the CytoScan HD microarray technique. Molecular karyotype did not reveal hypodiploidy, but identified other abnormalities such as duplication of chromosomal regions: 4q25q35.2, 6p23.3p11.1 and 8p23.3q24.21, and the loss of heterozygosity of short arm chromosome 9. In two regions of the chromosome biallelic deletions were found at 9p21.3, including the CDKN2A, CDKN2B, IFNA1, MTAP genes and at 10q23.31, containing PTEN. The child died 9 days after diagnosis. Bone marrow biopsy, GTG banding, FISH techniques, and molecular karyotyping were used to make an accurate diagnosis. This case documents a rapid progression of the disease and unfavorable results of T-cell acute lymphoblastic leukemia with hypodiploidy.