RT Book, Section A1 Fraser, James W. A1 Murphy, Janet E. A1 Attar, Eyal C. A2 Chabner, Bruce A. A2 Longo, Dan L. SR Print(0) ID 1127647891 T1 Acute Lymphoblastic Leukemia and Lymphoma T2 Harrison's Manual of Oncology, 2e YR 2016 FD 2016 PB McGraw-Hill Education PP New York, NY SN 9780071793254 LK hemonc.mhmedical.com/content.aspx?aid=1127647891 RD 2024/11/10 AB Acute lymphoblastic leukemia (ALL) is a highly aggressive neoplasm of hematopoietic cells of lymphoid lineage. Collections of abnormal T- or B lymphoblasts may be found in the bone marrow, peripheral blood, and other extramedullary sites. ALL is predominantly a childhood cancer, with two-thirds of new cases diagnosed in children younger than 15 years of age. ALL was uniformly fatal until the 1960 but, due to advances in chemotherapy and supportive care, is now cured in over 80% of children. Adults diagnosed with ALL, in contrast, have a poor overall prognosis. Important factors in assessing prognosis are the age of the patient, type of lymphoid cell involved (T cell vs B cell), and the presence of high-risk cytogenetic markers, such as the t(9;22) (BCR–ABL) translocation. Burkitt's lymphoma, a malignancy of mature B cells, has been historically classified as a B-ALL due to its high-grade leukemia-like features but is both diagnostically and prognostically a separate entity from precursor B-ALL. Burkitt's lymphoma is addressed in the chapter on non-Hodgkin lymphomas.