La leucémie lymphoblastique aigue

Abstract

Acute lymphoblastic leukemia is associated with the uncontrolled spread of lymphoblasts invading the bone marrow. This results in clonal reproduction of hematopoietic progenitors, which become unable to differentiate into mature cells. The morphological classification of the FAB group distinguishes three types of ALL based on cell size, cytoplasm, nuclei, basal cytoplasm and the presence of vacuoles. The altered expression, by leukemia cells, of membranous or intracytoplasmic antigens grouped together in a “CD” makes it possible to determine whether the lymphocytes belong to the B or T line and to determine the stage of their differentiation. The purpose of this test is to investigate possible chromosomal abnormalities that can determine the type of leukemia. The study of blast cells is carried out systematically because it is the basis of the WHO 2016 classification for ALL-B. Karyotyping is performed on myeloid blast cells, which makes it possible to search for quantitative and qualitative abnormalities of the chromosomes. At least two cells to confirm the same extra chromosome or the same structural abnormality. At least 3 cells to confirm the loss of the same chromosome. It is also possible to use the BCR-ABL1, ETV6-RUNX1 and TCF3-PBX1 fusion probes. In addition, RUNX1-RUNX1T1 probes can detect chromosomal amplifications in chromosome 21. FISH can also confirm a hyperploidy-like karyotype by attaching the probes to the centromere. Regarding the treatment of this disease, the aim is to reduce the number of leukemia cells that may persist in patients in a state of remission. Stem cell transplantation is only used in certain cases of ALL at risk of relapse. The transplant often involves the administration of chemotherapy combined with radiation therapy, followed by a transplant of stem cells from a donor.