ETP-ALL (Early T-cell precursor acute lymphoblastic leukemia)
ETP-ALL is currently defined by a distinctive phenotype characterized by a lack of expression of the T-lineage cell surface markers CD1a and CD8, weak or absent expression of CD5 and aberrant expression of one or more myeloid or stem cell markers (Coustan-Smith et al., 2009).
Early T-cell precursors (ETPs) are immature progenitors that have recently immigrated from the bone marrow to the thymus and which retain a multilineage differentiation potential (T-lymphoid, natural killer, dendritic and myeloid cell differentiation potential).
There is currently no consensus on the prognosis of ETP-ALL. Initial prognostic studies between 2009 and 2012 reported a negative prognostic impact on response rate and survival (Coustan-Smith et al., 2009, Inukai et al., 2012; Ma et al., 2012) and a higher risk of relapse (Allen and al., 2013).
ETP-ALL cases are currently identified through the phenotype of blast cells : CD1a-, CD8-, CD5- /weak, and positivity for one or more stem cell and/or myeloid antigens (CD117, CD34, HLA-DR, CD13, CD33, CD11b, and/or CD65). ETP-ALL typically also express CD2, CD7 and cytoplasmic CD3 and may express CD4.
In case 1 blasts are gated from CD45 population in red. these blasts are positive for cCD3 , MPO , CD7, CD34CD117, CD38, CD2, CD11B and CD13dim while negative for CD5, CD33, HLA-DR, CD123, CD1a, CD56, CD19, CD22, CD16 and Tdt.
In case 2 blasts are gated from CD45 population in red. these blasts are positive for cCD3, CD7, CD34, CD33, CD117dim, CD2, CD11B, HLA-DR while negative for CD5, CD1a, CD56, CD19, CD65, cCD79a, CD8 and CD4.
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