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Understanding leukemia

Types of leukemia: an overview

“Leukemia” is not one disease but the umbrella name for a group of diseases. This topic puts all the types on one map: how they are named, how they differ from each other, and where on this site you can read more about each one.

Last updated: ~6 min read
On a dark navy background, in front of a translucent human silhouette, four softly glowing groups of cells: two dense and fast, two sparse and calm; red-orange tones dominate one group and blue tones another, with a faint DNA helix behind.
Figure 1.Concept: the four main types of leukemia — where two speeds meet two cell families.

01Short answer

Leukemias are grouped by two main questions: how fast the disease develops (acute or chronic) and which cell family it starts in (myeloid or lymphoid). These two questions give the four main types: acute myeloid (AML), acute lymphoblastic (ALL), chronic myeloid (CML) and chronic lymphocytic (CLL) leukemia. There are also special subtypes (such as APL, a type of AML) and rare types (hairy cell leukemia, CMML, JMML, large granular lymphocytic leukemia and others). Modern classification (WHO 2022, ICC 2022) divides each type into smaller subgroups, mainly by genetic changes. In the United States, about 67,790 new cases of leukemia are expected in 2026; in adults AML and CLL are the most common, and in children ALL.

02Simple explanation

The name of a leukemia is like a two-part “address”. The first word tells you the speed: acute (develops quickly, immature cells) or chronic (develops slowly, more mature cells). The second tells you the family: myeloid or lymphoid (lymphoblastic / lymphocytic).

These two “coordinates” give four main types: AML — acute myeloid, ALL — acute lymphoblastic, CML — chronic myeloid and CLL — chronic lymphocytic leukemia. The vast majority of leukemias belong to one of these four.

Within each main type there are smaller “neighbourhoods” — subtypes. For example, APL is a special subtype of AML that needs completely different treatment. ALL can be B-cell or T-cell. Subtypes are defined mainly by the genetic changes in the leukemia cells.

There are also rare types: hairy cell leukemia, chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML), large granular lymphocytic leukemia, prolymphocytic leukemia and others. They are uncommon, but each has its own features and treatment.

The differences between types are huge: some need urgent treatment, others are simply monitored for years; some occur mainly in children, others in older adults. So when you hear the word “leukemia”, the first question is always: which type? Ask your hematologist for the exact name of your leukemia — this site is organised by that name too.

03Scientific explanation

Classification rests on four groups of information: morphology (how cells look under the microscope, the blast percentage), immunophenotype (CD markers from flow cytometry), cytogenetics (chromosome changes) and molecular genetics (gene mutations and fusions). Clinical information — such as previous chemotherapy or radiation, or an inherited predisposition — is also taken into account.

Two main international systems are in use: the WHO 5th edition (2022) and the International Consensus Classification (ICC, 2022). They agree on most points, but there are differences — for example, the blast threshold for genetically defined AML subtypes (WHO sets no threshold for many genetic types, while the ICC usually uses 10%) and whether CML keeps an accelerated phase (the ICC keeps it; WHO has dropped it). Your report usually states which system was used.

According to US SEER estimates for 2026, about 67,790 new cases of leukemia are expected: AML about 22,720, CLL 22,760, CML 9,650 and ALL 6,250; the rest are other and unspecified types. The median age at diagnosis for leukemia overall is 68, but it varies greatly by type: 18 for ALL, 67 for CML, 70 for AML and 71 for CLL. People under 20 make up about 7.4% of all cases, but more than half (52.1%) of ALL cases. These figures apply to the US population and may differ in other countries.

In children the picture is different: according to the American Cancer Society, about 3 in 4 childhood leukemias are ALL, and most of the rest are AML; chronic leukemias are rare in children. Among the rare types, hairy cell leukemia is diagnosed in about 1,200–1,300 people a year in the US. Classification is constantly being updated: new genetic findings allow new subtypes to be defined and treatment to be chosen more precisely.

04What happens in the body?

The four main types

AML — the most common acute leukemia in adults; ALL — the most common leukemia in children; CML — a chronic leukemia driven by BCR::ABL1 that is kept under control for years with targeted drugs; CLL — one of the most common leukemias in adults in Western countries, often slow-growing.

On a dark background, glowing groups of cells of different sizes are linked by lines of light; small branches split off from large central groups, with a few small cells of a different colour at the edges.
Figure 2.A “map” of leukemias: the main types, their subtypes and the rare types are all connected.

Subtypes: genetics takes centre stage

Within the same main type, subtypes can respond differently to treatment. For example, APL, Philadelphia-positive ALL or AML with an NPM1 mutation each call for a specific approach. That is why it is important to wait for genetic test results after diagnosis.

Rare types

Hairy cell leukemia, CMML, JMML, large granular lymphocytic leukemia, prolymphocytic leukemia, mixed phenotype acute leukemia, blastic plasmacytoid dendritic cell neoplasm and others. Because they are rare, an opinion from an experienced centre is especially valuable when treating them.

How can you find out your type?

Ask your doctor to write down the full name of the leukemia, its subtype and the main genetic findings. This will help you find the right topic on this site, get a second opinion and understand your treatment plan.

05How is a leukemia’s “address” worked out?

Doctors build the name of a leukemia from the answers to four questions.

Speed — Acute or chronic?1SpeedAcute or chronic?
Family — Myeloid or lymphoid? B or T?2FamilyMyeloid or lymphoid? B or T?
Genetics — Which chromosome and gene changes are present?3GeneticsWhich chromosome and gene changes are present?
Full name — A precise diagnosis under the WHO/ICC classification.4Full nameA precise diagnosis under the WHO/ICC classification.
Acute leukemiasAML (including APL), ALL (B and T), MPAL.
Chronic leukemiasCML, CLL, hairy cell leukemia and others.
Rare and borderline typesCMML, JMML, LGL leukemia, BPDCN and more.

06The main types in one table

TypeAcute / chronicFamilyMedian age at diagnosis (US)Estimated new US cases, 2026Key feature
AMLAcuteMyeloid7022,720The most common acute leukemia in adults
APL (a subtype of AML)AcuteMyeloidUsually younger than in other AMLIncluded in AML casesUrgent treatment; very good results
ALLAcuteLymphoid (B / T)186,250The most common leukemia in children
CMLChronicMyeloid679,650BCR::ABL1; targeted drugs
CLLChronicLymphoid (B)7122,760Often slow-growing; sometimes monitoring only
Hairy cell leukemiaChronicLymphoid (B)About 55About 1,200–1,300Rare; BRAF V600E; responds well to treatment

* Figures are US data from SEER (2026 estimates) and NCI; they may differ in other countries. The median age is the midpoint, with equal numbers of people on either side; any type can occur at any age.

07Key terms

Classification
Sorting diseases into groups by shared criteria.
AML
Acute myeloid leukemia.
ALL
Acute lymphoblastic leukemia.
CML
Chronic myeloid leukemia.
CLL
Chronic lymphocytic leukemia.
APL
Acute promyelocytic leukemia; a subtype of AML.
Subtype
A narrower group within a main type, often defined by a genetic feature.
WHO 2022
The World Health Organization classification, 5th edition.
ICC 2022
The International Consensus Classification.
Median age
The age at which half of patients are younger and half are older.

08Key points

  • Leukemia is a group of diseases; the first question is always “which type?”.
  • Types are grouped by speed (acute / chronic) and family (myeloid / lymphoid).
  • The four main types are AML, ALL, CML and CLL.
  • Subtypes are defined mainly by genetic changes, and they affect treatment.
  • There are also rare types: hairy cell leukemia, CMML, JMML, LGL leukemia and others.
  • In adults AML and CLL are most common; in children, ALL.
  • Ask your doctor to write down the full name of your leukemia and its genetic findings.

09Frequently asked questions

Which type of leukemia is the “best” and which is the “worst”?

There is no simple ranking. Within each type, results vary widely depending on the subtype, genetics, age and response to treatment. For example, APL, a subtype of AML, has very good results with the right treatment. Discuss your own situation with your doctor, based on your specific findings.

Can a person have two types of leukemia?

This is very rare. Occasionally there is mixed phenotype leukemia (features of both families) or two different blood disorders one after the other. Such cases need careful assessment at an experienced centre.

Can the type of leukemia change over time?

The main type usually does not change. But chronic diseases can progress — for example, untreated CML can move into the blast phase, and MDS can turn into AML. At relapse, the genetic profile can also change, which is why tests are repeated.

Why do classification systems change so often?

Because science moves on: new genetic findings make it possible to separate diseases more precisely and choose treatment more accurately. That is good news for patients. If your report uses an older or newer name, ask your doctor to explain.

What if my type is not on this site?

You will find general information on rare types in “Rare types of leukemia”. For precise information, turn to your hematologist and to reliable international sources (NCI, ACS, NHS).

Are childhood and adult leukemias the same disease?

The names may be the same, but the biology, genetic changes and treatment results often differ. Children are treated by pediatric hematologist-oncologists, and results are very good overall.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. What is the full name of my leukemia and its subtype?

  2. What is the standard treatment for this subtype?

  3. Which reliable sources about this type would you recommend?

  4. Can I have the name of my diagnosis in writing?

My questions

12Sources

  1. National Cancer Institute (NCI). Leukemia — Patient Version
  2. National Cancer Institute (NCI), SEER. Cancer Stat Facts: Leukemia
  3. National Cancer Institute (NCI), SEER. Cancer Stat Facts: Acute Myeloid Leukemia (AML)
  4. National Cancer Institute (NCI), SEER. Cancer Stat Facts: Acute Lymphocytic Leukemia (ALL)
  5. National Cancer Institute (NCI), SEER. Cancer Stat Facts: Chronic Myeloid Leukemia (CML)
  6. National Cancer Institute (NCI), SEER. Cancer Stat Facts: Chronic Lymphocytic Leukemia (CLL)
  7. American Cancer Society. Leukemia
  8. American Cancer Society. Leukemia in Children
  9. National Cancer Institute (NCI). Hairy Cell Leukemia Treatment (PDQ®) — Health Professional Version
  10. American Society of Hematology (ASH). Leukemia
  11. World Health Organization / IARC. WHO Classification of Tumours Online
  12. Leukemia (Nature) — WHO 5th edition. WHO Classification of Haematolymphoid Tumours: Myeloid and Histiocytic/Dendritic Neoplasms
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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