Distinct immunophenotype of early T-cell progenitors in T lymphoblastic leukemia/lymphoma may predict FMS-like tyrosine kinase 3 mutations

CD117 Expression Is a Sensitive but Nonspecific Predictor of FLT3 Mutation in T Acute Lymphoblastic Leukemia and T/Myeloid Acute Leukemia

“…Seven cases of FLT3-mutated acute leukemia in this study had a T/myeloid phenotype, and none of these cases had monoclonal TCR-γ gene rearrangements. These findings are in accord with the findings in a recent study by Zaremba and colleagues 16 who, in an abstract, reported 3 FLT3-mutated cases thought to arise from early thymic T-cell progenitors that have T-cell and myeloid potential. These cases are also consistent with newly proposed models of lineage commitment.…”

Mixed-Phenotype Acute Leukemia: Diagnostic Criteria and Pitfalls

“…Studies of FLT3 mutations in T-ALL found that these mutations correlate with an early T-precursor (ETP)like immunophenotype, and most cases expressed MPO. 38,39 FLT3 mutations have also been detected in several cases of bona fide ETP-ALL. 40 Based on 2016 WHO criteria, 7 the presence or absence of MPO is a discriminating factor between the diagnosis of ETP-ALL and MPAL, T/myeloid.…”

Lineage determination in mixed phenotype acute leukemia: Response to marcondes et al.

“…Importantly, this case may represent an emerging, increasingly recognized entity of early T-cell precursor acute lymphoblastic leukemia/lymphoma, (5) characterized by an immunophenotype of CD1a 2 /intracellular CD3 1 /CD7 1 /CD34 1 /CD117 1 / Tdt 1 , corresponding to the stage of earliest thymic T-cell progenitors that possess myeloid lineage potential (6). Recent studies from our group (7) and the MD Anderson group (8) have found that many of these early T-cell precursor lymphoblastic leukemia/lymphoma cases can be alternatively classified as MPAL, T/myeloid, on the basis of a small subset of blasts expressing MPO, as in our case. Interestingly, these cases have frequent FLT3 mutation.…”

“…Therefore, early T-cell precursor lymphoblastic leukemia/lymphoma seems biologically closely related to MPAL, T/myeloid, which likely represents one disease with variable degree of myeloid differentiation, as illustrated in our case with more myeloid differentiation in lymph node and more T-lymphoid differentiation in bone marrow. This leukemia entity might be adequately distinctive to be considered provisionally as a separate Cytometry Part B (Clinical Cytometry) 86B:150-151 (2014) V C 2014 International Clinical Cytometry Society leukemia type with recurrent genetic abnormalities (7)(8)(9) in the future version of the WHO classification scheme.…”