Acutevs chronic leukemia
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leukemia AND classification
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American Cancer Society acute versus chronic leukemia differences
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Acute vs chronic leukemia
| Feature | Acute leukemia | Chronic leukemia |
|---|---|---|
| Cell maturity | Predominantly immature precursor cells (blasts) | More mature, differentiated leukemic cells |
| Course | Rapid progression, usually days to weeks | Often slower progression over months to years |
| Presentation | Often sudden and symptomatic | May be found incidentally on a routine CBC |
| Bone marrow effect | Marrow rapidly replaced by blasts, causing marrow failure | Marrow and blood cell counts rise gradually; marrow function may initially be preserved |
| Typical symptoms | Fatigue, pallor, fever/infections, bruising/bleeding, bone pain | Fatigue, weight loss, night sweats, early satiety from splenomegaly, sometimes no symptoms |
| Blood counts | Anemia, thrombocytopenia, neutropenia may occur; WBC can be high, normal, or low | Persistent elevated WBC count is common; anemia or thrombocytopenia tend to occur later |
| Urgency | Usually a medical emergency requiring prompt specialist treatment | Some types can initially be monitored; treatment timing depends on subtype and stage |
| Main examples | ALL - acute lymphoblastic leukemia; AML - acute myeloid leukemia | CLL - chronic lymphocytic leukemia; CML - chronic myeloid leukemia |
| Treatment approach | Intensive induction therapy, often consolidation, targeted therapy, and sometimes stem-cell transplant | Targeted drugs, immunotherapy, chemotherapy in selected cases, or watchful waiting for some CLL cases |
Key concept
The terms acute and chronic describe the disease behavior and cell maturation, not simply duration. Acute leukemia is fast-growing and dominated by blasts. Chronic leukemia generally has more mature cells and a more gradual course. Leukemias are also classified by lineage: lymphoid or myeloid. The American Cancer Society overview summarizes this two-axis classification.
Important exception
Chronic leukemia can transform into an aggressive blast phase. For example, in CML, blast phase represents progression to an acute leukemia-like state and is defined by more than 20% blasts in blood or bone marrow.
A definitive distinction needs a CBC with peripheral smear, bone-marrow examination, flow cytometry, cytogenetics, and molecular testing.
Any no for classification
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Do you mean “how many ways leukemia is classified?”
There are 2 main classifications:
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By clinical course
- Acute leukemia
- Chronic leukemia
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By cell lineage
- Lymphoid leukemia
- Myeloid leukemia
So the four major types are:
- Acute lymphoblastic leukemia (ALL)
- Acute myeloid leukemia (AML)
- Chronic lymphocytic leukemia (CLL)
- Chronic myeloid leukemia (CML)
Fab and who reference for leukemia
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WHO classification myeloid and lymphoid neoplasms 2022 acute leukemia FAB classification AML M0 M7 official
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FAB and WHO classification of leukemia
1. FAB classification
FAB = French-American-British classification.
It is an older, morphology-based system using bone marrow/peripheral smear appearance, cytochemistry, and cell maturation.
It is an older, morphology-based system using bone marrow/peripheral smear appearance, cytochemistry, and cell maturation.
A. Acute lymphoblastic leukemia (ALL)
| FAB subtype | Description |
|---|---|
| L1 | Small, uniform lymphoblasts. Common in children. |
| L2 | Larger, variable-sized lymphoblasts with irregular nuclei. More common in adults. |
| L3 | Burkitt-type blasts: deeply basophilic, vacuolated cytoplasm. Associated with mature B-cell phenotype. |
B. Acute myeloid leukemia (AML)
| FAB subtype | Name |
|---|---|
| M0 | Minimally differentiated AML |
| M1 | AML without maturation |
| M2 | AML with maturation |
| M3 | Acute promyelocytic leukemia, APL |
| M4 | Acute myelomonocytic leukemia |
| M4Eo | M4 with eosinophilia, classically inv(16) |
| M5 | Acute monocytic/monoblastic leukemia |
| M6 | Acute erythroid leukemia, erythroleukemia |
| M7 | Acute megakaryoblastic leukemia |
Remember:
- M3/APL is commonly associated with PML::RARA and can cause severe DIC.
- FAB terminology is still often used in exams and for descriptive morphology, but it is no longer the main diagnostic classification.
2. WHO classification
The current reference is the WHO 5th edition classification of haematolymphoid tumours (WHO-HAEM5, 2022). It classifies leukemia using an integrated approach:
- Morphology
- Cytochemistry
- Immunophenotyping by flow cytometry
- Cytogenetics
- Molecular/genetic abnormalities
- Clinical setting, including prior cytotoxic therapy and germline predisposition
Thus, WHO classification is more biologically and clinically meaningful than FAB. The WHO 2022 overview and CAP summary describe the present emphasis on molecularly defined entities.
WHO 2022: main AML groups
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AML with defining genetic abnormalities
- Examples: AML with PML::RARA, RUNX1::RUNX1T1, CBFB::MYH11, KMT2A rearrangement, DEK::NUP214, etc.
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AML, myelodysplasia-related
- Defined by characteristic genetic abnormalities, cytogenetic abnormalities, or prior myelodysplastic syndrome/myelodysplastic-myeloid neoplasm.
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AML defined by differentiation
- Includes morphologic entities such as AML with minimal differentiation, without maturation, with maturation, myelomonocytic, monocytic, erythroid, and megakaryoblastic differentiation.
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Myeloid sarcoma
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Myeloid neoplasms post cytotoxic therapy
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Myeloid neoplasms with germline predisposition
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Myeloid proliferation associated with Down syndrome
WHO classification of ALL
WHO mainly divides ALL into:
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B-lymphoblastic leukemia/lymphoma (B-ALL/LBL)
- Classified further by genetic abnormalities, such as BCR::ABL1-positive, ETV6::RUNX1, hyperdiploidy, hypodiploidy, KMT2A-rearranged, etc.
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T-lymphoblastic leukemia/lymphoma (T-ALL/LBL)
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Mixed phenotype acute leukemia (MPAL)
- Blasts express markers of more than one lineage, for example myeloid plus B-lymphoid or T-lymphoid.
One-line exam answer
FAB is an older morphology and cytochemistry-based classification: ALL is L1-L3 and AML is M0-M7. WHO classification is the modern integrated system based on morphology, immunophenotype, cytogenetic and molecular genetic abnormalities, and clinical context.
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