Acute lymphoblastic leukaemia: prognostic factors

What it is

Acute lymphoblastic leukemia is a malignant disease of the bone marrow in which early lymphoid precursors proliferate and replace the normal hematopoietic cells of the marrow. It is more common in the pediatric age group. WHO subdivides it into two types by cell of origin: B lymphoblastic leukemia, 80%-85% of the cases, and T lymphoblastic leukemia, 15%-20%. The more common one is also the better one.

The WHO 2016 classification names B-lymphoblastic leukemia or lymphoma, NOS, then a set with recurrent genetic abnormalities: t(9;22)(q34.1;q11.2) BCR-ABL1; t(v;11q23.3) with KMT2A rearranged; t(12;21)(p13.2;q22.1) ETV6-RUNX1; hyperdiploidy; hypodiploidy; t(5;14)(q31.1;q32.3) IL3-IGH; and t(1;19)(q23;p13.3) TCF3-PBX1.

How it presents

Fatigue and bruises bring the child in, and the CBC shows the marrow has been taken over: a hemoglobin of 7.8 g/dl, a WBC of 26x10^9/L and a platelet count of 14x10^9/L.

How it is diagnosed

The peripheral blood film shows circulating blast cells, and the bone marrow biopsy shows the blast percentage, which can reach 92%. The immunophenotype on that marrow is what names the disease, such as T cell lymphoblastic leukemia (T-ALL), and the cytogenetic analysis on the aspirate adds the genotype, such as hyperdiploidy.