Editing Leukemia (section)

==Classification==
<!-- Incorrect use of [[WP:ITALICS]] throughout this section -->
{| class="wikitable" style="margin-left:15px; text-align:center"
|+Four major kinds of leukemia
! Cell type !! Acute !! Chronic
 |-
 | '''Lymphocytic leukemia'''<br />(or "lymphoblastic") || [[Acute lymphoblastic leukemia]]<br /> (ALL) || [[B-cell chronic lymphocytic leukemia|Chronic lymphocytic leukemia]]<br /> (CLL)
 |-
 | '''Myelogenous leukemia'''<br />("myeloid" or "nonlymphocytic") || [[Acute myeloid leukemia|Acute myelogenous leukemia]] <br />(AML or myeloblastic) || [[Chronic myelogenous leukemia]]<br /> (CML)
|}
[[File:Acute leukemia 1.webm|thumb|upright=1.4|An explanation of acute leukemia]]

===General classification===
Clinically and pathologically, leukemia is subdivided into a variety of large groups. The first division is between its ''[[Acute (medical)|acute]]'' and ''[[chronic (medicine)|chronic]]'' forms:<ref name=":1">{{Cite web |title=Questions and Answers About Leukemia |url=https://www.cdc.gov/nceh/radiation/phase2/mleukemi.pdf |url-status=live |archive-url=https://web.archive.org/web/20210730115224/https://www.cdc.gov/nceh/radiation/phase2/mleukemi.pdf |archive-date=July 30, 2021 |access-date=August 8, 2021 |website=[[Centers for Disease Control and Prevention]]}}</ref>
* [[Acute leukemia]] is characterized by a rapid increase in the number of immature blood cells. The crowding that results from such cells makes the bone marrow unable to produce healthy blood cells resulting in low [[hemoglobin]] and low [[platelet]]s. Immediate treatment is required in acute leukemia because of the rapid progression and accumulation of the [[malignant cell]]s, which then spill over into the bloodstream and spread to other organs of the body. Acute forms of leukemia are the most common forms of [[childhood leukemia|leukemia in children]].
* [[Chronic leukemia]] is characterized by the excessive buildup of relatively mature, but still abnormal, [[white blood cell]]s (or, more rarely, [[red blood cell]]s). Typically taking months or years to progress, the cells are produced at a much higher rate than normal, resulting in many abnormal white blood cells. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy. Chronic leukemia mostly occurs in older people but can occur in any age group.

Additionally, the diseases are subdivided according to which kind of blood cell is affected. This divides leukemias into [[Acute lymphoblastic leukemia|lymphoblastic]] or ''[[lymphocytic leukemia]]s'' and [[Myeloid leukemia|myeloid]] or ''[[myelogenous leukemia]]s'':<ref name=":1" />
* In lymphoblastic or [[lymphocytic leukemia]]s, the cancerous change takes place in a type of marrow cell that normally goes on to form [[lymphocyte]]s, which are infection-fighting immune system cells. Most lymphocytic leukemias involve a specific subtype of lymphocyte, the [[B&nbsp;cell]].
* In myeloid or [[myelogenous leukemia]]s, the cancerous change takes place in a [[myeloid cells|type of marrow cell]] that normally goes on to form [[red blood cell]]s, some other types of white cells, and [[platelet]]s.

Combining these two classifications provides a total of four main categories. Within each of these main categories, there are typically several subcategories. Finally, some rarer types are usually considered to be outside of this classification scheme.<ref name=":1" /><ref>{{Cite web|title=Leukemia — Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/leukemia/symptoms-causes/syc-20374373|access-date=2021-08-08|website=Mayo Clinic|language=en}}</ref>

===Specific types===
* [[Acute lymphoblastic leukemia]] (ALL) is the most common type of leukemia in young children. It also affects adults, especially those 65 and older. Standard treatments involve [[chemotherapy]] and [[radiotherapy]]. Subtypes include [[precursor B acute lymphoblastic leukemia]], [[precursor T acute lymphoblastic leukemia]], [[Burkitt's leukemia]], and [[acute biphenotypic leukemia]]. While most cases of ALL occur in children, 80% of deaths from ALL occur in adults.<ref>{{cite web |url= https://www.cancer.org/cancer/acute-lymphocytic-leukemia/about/key-statistics.html/|title= Key Statistics for Acute Lymphocytic Leukemia (ALL)|date=8 January 2019 |website=American Cancer Society |access-date=9 December 2019}}</ref>
*  [[Chronic lymphocytic leukemia]] (CLL) most often affects adults over the age of 55. It sometimes occurs in younger adults, but it almost never affects children. Two-thirds of affected people are men. The five-year survival rate is 85%.<ref>{{cite web | url = http://seer.cancer.gov/statfacts/html/clyl.html | title = Finding Cancer Statistics » Cancer Stat Fact Sheets »Chronic Lymphocytic Leukemia | archive-url = https://web.archive.org/web/20080416053309/http://seer.cancer.gov/statfacts/html/clyl.html| archive-date=16 April 2008 | work = National Cancer Institute }}</ref> It is incurable, but there are many effective treatments. One subtype is [[B-cell prolymphocytic leukemia]], a more aggressive disease.
* [[Acute myelogenous leukemia]] (AML) occurs far more commonly in adults than in children, and more commonly in men than women. It is treated with chemotherapy. The five-year survival rate is 20%.<ref>{{cite web |url=https://www.cancerresearchuk.org/about-cancer/acute-myeloid-leukaemia-aml/survival/|title=Survival: Acute Myeloid Leukaemia |date=10 July 2019 |website=Cancer Research UK |access-date=2 December 2019}}</ref> Subtypes of AML include [[acute promyelocytic leukemia]], [[acute myeloblastic leukemia]], and [[acute megakaryoblastic leukemia]].
* [[Chronic myelogenous leukemia]] (CML) occurs mainly in adults; a very small number of children also develop this disease. It is treated with [[imatinib]] (Gleevec in United States, Glivec in Europe) or other drugs.<ref>{{cite web|url=http://www.novartisoncology.com|title=Novartis Oncology|url-status=live|archive-url=https://web.archive.org/web/20131105145436/http://www.novartisoncology.com/|archive-date=5 November 2013}}</ref> The five-year survival rate is 90%.<ref>{{cite web | vauthors = Moyer P | date = 12 June 2006 | url = http://www.medscape.com/viewarticle/536049 | title = Patients with Chronic Myelogenous Leukemia Continue to Do Well on Imatinib at 5-Year Follow-Up | archive-url = https://web.archive.org/web/20130515063623/http://www.medscape.com/viewarticle/536049 | archive-date = 15 May 2013 | work = Medscape Medical News }}</ref><ref>{{cite web | url = http://professional.cancerconsultants.com/conference_asco_2006.aspx?id=37519 | title = Updated Results of Tyrosine Kinase Inhibitors in CML | archive-url = https://web.archive.org/web/20071229125528/http://professional.cancerconsultants.com/conference_asco_2006.aspx?id=37519 | archive-date=29 December 2007 | work = ASCO 2006 Conference Summaries }}</ref> One subtype is [[chronic myelomonocytic leukemia]].
* [[Hairy cell leukemia]] (HCL) is sometimes considered a subset of chronic lymphocytic leukemia, but does not fit neatly into this category. About 80% of affected people are adult men. No cases in children have been reported. HCL is incurable but easily treatable. Survival is 96% to 100% at ten years.<ref name="pmid16245328">{{cite journal | vauthors = Else M, Ruchlemer R, Osuji N, Del Giudice I, Matutes E, Woodman A, Wotherspoon A, Swansbury J, Dearden C, Catovsky D | title = Long remissions in hairy cell leukemia with purine analogs: a report of 219 patients with a median follow-up of 12.5 years | journal = Cancer | volume = 104 | issue = 11 | pages = 2442–8 | date = December 2005 | pmid = 16245328 | doi = 10.1002/cncr.21447 | s2cid = 43282431 | doi-access = free }}</ref>
* [[T-cell prolymphocytic leukemia]] (T-PLL) is a very rare and aggressive leukemia affecting adults; somewhat more men than women are diagnosed with this disease.<ref>{{cite journal | vauthors = Matutes E | title = T-cell Prolymphocytic Leukemia | journal = Cancer Control | volume = 5 | issue = 1 | pages = 19–24 | date = January 1998 | pmid = 10761013 | doi = 10.1177/107327489800500102 | url = http://www.moffitt.org/moffittapps/ccj/v5n1/article2.html | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20090211044933/http://www.moffitt.org/moffittapps/ccj/v5n1/article2.html | archive-date = 11 February 2009 }}</ref> Despite its overall rarity, it is the most common type of mature [[T cell]] leukemia;<ref name="pmid15716243">{{cite journal | vauthors = Valbuena JR, Herling M, Admirand JH, Padula A, Jones D, Medeiros LJ | title = T-cell prolymphocytic leukemia involving extramedullary sites | journal = American Journal of Clinical Pathology | volume = 123 | issue = 3 | pages = 456–464 | date = March 2005 | pmid = 15716243 | doi = 10.1309/93P4-2RNG-5XBG-3KBE | url = http://www.medscape.com/viewarticle/501092 | url-status = live | doi-access = free | archive-url = https://web.archive.org/web/20130515093513/http://www.medscape.com/viewarticle/501092 | archive-date = 15 May 2013 }}</ref> nearly all other leukemias involve [[B cells]]. It is difficult to treat, and the median survival is measured in months.
* [[Large granular lymphocytic leukemia]] may involve either T-cells or [[NK cell]]s; like hairy cell leukemia, which involves solely B cells, it is a rare and [[Indolent condition|indolent]] (not aggressive) leukemia.<ref name="who1">{{cite book | vauthors = Jaffe ES, Harris NL, Stein H, Vardiman JW | collaboration = World Health Organization, International Agency for Research on Cancer |title=Pathology and genetics of tumours of haematopoietic and lymphoid tissues |publisher=IARC Press |location=Lyon |year=2001 |series=World Health Organization Classification of Tumors |volume=3 |isbn=978-92-832-2411-2 |url=https://books.google.com/books?id=XSKqcy7TUZUC}}</ref>
* [[Adult T-cell leukemia/lymphoma|Adult T-cell leukemia]] is caused by [[human T-lymphotropic virus]] (HTLV), a virus similar to [[human immunodeficiency virus|HIV]]. Like HIV, HTLV infects CD4+ T-cells and replicates within them; however, unlike HIV, it does not destroy them. Instead, HTLV "immortalizes" the infected T-cells, giving them the ability to proliferate abnormally. Human T-cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world.{{citation needed|date=March 2021}}
* [[Clonal eosinophilia]]s (also called ''clonal hypereosinophilias'') are a group of blood disorders characterized by the growth of [[eosinophil]]s in the [[bone marrow]], blood, and/or other tissues.   They may be [[pre-malignant|pre-cancerous]] or [[malignant|cancerous]]. Clonal eosinophilias involve a [[Clone (cell biology)|"clone"]] of eosinophils, i.e., a group of genetically identical eosinophils that all grew from the same [[mutated]] ancestor cell.<ref name="pmid28028030">{{cite journal | vauthors = Reiter A, Gotlib J | title = Myeloid neoplasms with eosinophilia | journal = Blood | volume = 129 | issue = 6 | pages = 704–714 | date = February 2017 | pmid = 28028030 | doi = 10.1182/blood-2016-10-695973 | doi-access = free }}</ref> These disorders may evolve into [[chronic eosinophilic leukemia]] or may be associated with various forms of [[myeloid]] neoplasms, [[lymphoid]] neoplasms, [[myelofibrosis]], or the [[myelodysplastic syndrome]].<ref name="pmid26486351">{{cite journal | vauthors = Gotlib J | title = World Health Organization-defined eosinophilic disorders: 2015 update on diagnosis, risk stratification, and management | journal = American Journal of Hematology | volume = 90 | issue = 11 | pages = 1077–89 | date = November 2015 | pmid = 26486351 | doi = 10.1002/ajh.24196 | s2cid = 42668440 | doi-access = free }}</ref><ref name="pmid27069254">{{cite journal | vauthors = Arber DA, Orazi A, Hasserjian R, Thiele J, Borowitz MJ, Le Beau MM, Bloomfield CD, Cazzola M, Vardiman JW | title = The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia | journal = Blood | volume = 127 | issue = 20 | pages = 2391–2405 | date = May 2016 | pmid = 27069254 | doi = 10.1182/blood-2016-03-643544 | s2cid = 18338178 | doi-access = free }}</ref><ref name="pmid28028030"/>

===Pre-leukemia===
* [[Transient myeloproliferative disease]], also termed transient leukemia, involves the abnormal proliferation of a [[Clone (cell biology)|clone]] of non-cancerous [[megakaryoblast]]s. The disease is restricted to individuals with [[Down syndrome]] or genetic changes similar to those in Down syndrome, develops in a baby during pregnancy or shortly after birth, and resolves within 3 months or, in ~10% of cases, progresses to [[acute megakaryoblastic leukemia]]. Transient myeloid leukemia is a pre-leukemic condition.<ref name="pmid27510823">{{cite journal | vauthors = Bhatnagar N, Nizery L, Tunstall O, Vyas P, Roberts I | title = Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update | journal = Current Hematologic Malignancy Reports | volume = 11 | issue = 5 | pages = 333–341 | date = October 2016 | pmid = 27510823 | pmc = 5031718 | doi = 10.1007/s11899-016-0338-x }}</ref><ref name="pmid28179280">{{cite journal | vauthors = Crispino JD, Horwitz MS | title = GATA factor mutations in hematologic disease | journal = Blood | volume = 129 | issue = 15 | pages = 2103–10 | date = April 2017 | pmid = 28179280 | pmc = 5391620 | doi = 10.1182/blood-2016-09-687889 }}</ref><ref name="pmid22867885">{{cite journal | vauthors = Seewald L, Taub JW, Maloney KW, McCabe ER | title = Acute leukemias in children with Down syndrome | journal = Molecular Genetics and Metabolism | volume = 107 | issue = 1–2 | pages = 25–30 | date = September 2012 | pmid = 22867885 | doi = 10.1016/j.ymgme.2012.07.011 }}</ref>
* [[Clonal hematopoiesis]] is a common age-related phenomenon with a low risk of progression to [[myelodysplastic syndrome]] (MDS) and leukemia.<ref>{{cite journal |vauthors=Weeks LD, Ebert BL |title=Causes and consequences of clonal hematopoiesis |journal=Blood |volume=142 |issue=26 |pages=2235–46 |date=December 2023 |pmid=37931207 |doi=10.1182/blood.2023022222 |doi-access=free |pmc=10862247 }}</ref> Once MDS has developed, the risk of progression to acute leukemia can be assessed using the International Prognostic Scoring System ([[International Prognostic Scoring System|IPSS]]).
* [[Monoclonal B-cell lymphocytosis]] has a low risk of progression to B-cell leukemia.