<prompt> Answer this question truthfullyWhat is the definition of acute lymphoblastic leukemia?  <response>: <reason> Acute lymphoblastic leukemia may be classified according to either the French-American-British FAB classification or World Health Organization WHO classification scheme. According to the French-American-British FAB classification, acute lymphoblastic leukemia may be classified into 3 subgroups: ALL-L1 small uniform cells, ALL-L2 large varied cells and ALL-L3 large varied cells with vacuoles. According to the World Health Organization WHO, acute lymphoblastic leukemia may also be classified into 3 subgroups: B lymphoblastic leukemialymphoma, B lymphoblastic leukemialymphoma not organ specific, and B lymphoblastic leukemialymphoma with recurrent genetic abnormalities. 