CD7 and T-cell acute lymphoblastic leukemia: T-cell acute lymphoblastic leukemia has been divided into four subtypes according to the European Group for the Immunological Classification of Leukemia (EGIL): pro-T EGIL T-I (cCD3+, CD7+), pre-T EGIL T-II (cCD3+, CD7+, and CD5/CD2+), cortical T EGIL T-III (cCD3+, Cd1a+, sCD3+/−), and mature-T EGIL T-IV (cCD3+, sCD3+, CD1a−) (2).