71 Introduction to Leukemias
Michelle To and Valentin Villatoro
Leukemia: Describes tumors that originate from the bone marrow.1
Lymphoma: Describes tumors that originate from the lymphatic tissues.1
The causes of acute leukemia are vast. There are a number of factors that can lead to the development of leukemia, such as: genetic mutations, environmental factors (e.g. exposure to drugs, chemicals, radiation), inherited syndromes (e.g. Down syndrome, fanconi anemia), viral infections (e.g. HIV), immunologic dysfunction (e.g. immunosuppressants), or idiopathic factors.1
There are different classification systems that exist to categorize acute and chronic leukemias. Two examples are the French-American-British (FAB) system and the World Health Organization (WHO) system.1-4
Note: Please be aware that these schemes are updated periodically and the sources used in this ebook may not reflect the most current classification systems used.
Leukemias are described as being “acute” or “chronic” and specified as to which cell lineage and maturation stage is affected.5
Table 1. Comparison of Acute and Chronic Leukemias.5,6
All ages affected
Involve immature cells
≥20%* blasts in PBS or BM
*WHO Classification Criteria
Mainly adults affected
Involve mature cells
≤20% blasts in PBS or BM
1. McKenzie SB. Introduction to hematopoietic neoplasms. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 424-45.
2. Roquiz W, Gandhi P, Kini AR. Acute leukemias. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 543-60.
3. Swerdlow SH, Campo E, Harris NL, Jaffe ES, Pileri SA, Stein H, et al. editors. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues Volume 2. 4th ed. International Agency for Research on Cancer (IARC); 2008.
4. Arber D, Orazi A, Hasserjian R, Thiele J, Borowitz MJ, Le Beau MM, et al. The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia. Blood [Internet]. 2016 May 19;127(20):2391–405. Available from: http://www.ncbi.nlm.nih.gov/pubmed/27069254
5. Gatter K, Cruz F, Braziel R. Introduction to leukemia and the acute leukemias. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 331-370.
6. Bentley G, Leclair SJ. Acute Myeloid Leukemias. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 500-21.