CD5 and acute lymphoblastic leukemia: Accordingly, the immunophenotype of early T-precursor lymphoblastic leukemia (ETP-ALL) must meet all of the following diagnostic criteria: expression of cytoplasmic CD3 (with rare surface CD3 expression), absent myeloperoxidase (MPO), lack of CD1a and CD8 expression, ≥ 25% of blasts with ≥ 1 stem cell or myeloid markers (i.e., CD34, CD117, CD13, CD65, CD11b, HLA-DR), and dim-to-negative CD5 expression [4].