ETP-ALL is characterized by the absence of both CD1a and CD8 (absent in more than 95% of leukemic cells), the absence or weak expression of CD5 (in ≤75% of total cells or 10 times less than in normal T cells), or the expression of at least one stem cell marker/stem cell: CD117, CD34, HLA-DR, CD13, CD33, CD11b, or CD65 (equal or more than 25% of total cells) [23]. Here, CD1A is linked to acute lymphoblastic leukemia.