Leukaemia

Overview

Leukemia is a common malignancy in children and adults that occurs when alterations in normal cell regulatory processes cause uncontrolled proliferation of hematopoietic stem cells in the bone marrow.

Definition

Leukaemia: Clonal proliferation of hematopoietic stem cells in the bone marrow
Acute Leukaemia: Clonal proliferation of hematopoietic stem cells in the bone marrow that develops rapidly, requires immediate treatment and often presents with symptoms. In acute leukaemia the cells in the bone marrow are immature (blasts).
Chronic Leukaemia: clonal proliferation of hematopoietic stem cells in the bone marrow that develops slowly, treatment may be delated and often presents asymptomatically. In chronic leukaemia the cells in the bone marrow are still able to mature.
Lymphoma: Heterogeneous group of haematological neoplasms, characterised by proliferation of malignantly transformed T or B lymphocytes. The proliferation occur typically in the lymph nodes unlike leukaemia which occir in the bone marrow and result in overcrowding.

**Leukaemia Overview**

What to notice
Detailed image description

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An introduction to Haematopoesis

Classification

Its important to know that Leukaemia can be divided into acute and chronic and then further divided into its cell lineage. Remember that this makes each of them very different diseases.

Acute leukaemia

Acute Myeloid leukaemia (adults)
Acute Lymphoblastic leukaemia (children)

Chronic Leukaemia

Chronic Myeloid leukaemia (adults)
Chronic Lymphoblastic leukaemia (older adults)

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a group of clonal bone marrow disorders characterized by ineffective blood cell production, dysplasia, and peripheral blood cytopenias, with a risk of progression to acute myeloid leukemia.

Leukemoid reaction

A leukemoid reaction is a marked increase in white blood cell count in response to severe infection, inflammation, or other stress, mimicking leukemia without being a blood cancer.

Acute lymphoblastic leukemia occurs more often in children, whereas the other subtypes are more common in adults.

SUMMARY OF MAJOR LEUKAEMIA
Subtype	Description	Typical Group affects
Acute lymphoblastic leukaemia	Blast cells on peripheral blood smear or bone marrow aspirate	Children (53% <20yo)
Acute Myelogenous leukaemia	Blast cells on peripheral blood smear or bone marrow aspirate; Auer rods on peripheral smear	Adults
Chronic lymphoblastic leukaemia	Clonal expansion of at least 5,000 B lymphocytes per μL (5.0 × 10⁹ per L) in the peripheral blood	Older adults (85% >65yo)
Chronic Myelogenous leukaemia	Philadelphia chromosome (BCR-ABL1fusion gene)	Adults

Clinical Presentation

The clinical presentation depends on the type of Leukaemia.

Acute Leukaemia – pancytopaenia

Acute Lymphoblastic Leukaemia (more common in children)

Fever
Lethargy
Bleeding
Hepatomegaly
Splenomegaly
Lymphadenopathy
Bone pain

Acute Myelogenous Leukaemia

Constitutional symptoms: Fever, Weight loss, Night sweats
Anaemia symptoms: Shortness of breath, chest pain
Thrombocytopaenia symptoms: excessive bruising, nosebleeds, or heavy menstrual periods in women
Less likely: Bone pain, hepatomegaly and splenomegaly

Patients will AML fall ill suddenly and deteriorate fast, because of Infection, Bleeding (low platelets) and Hyperviscosity.

Chronic Leukaemia – white cell count is high (but nonfunctioning)

Chronic Lymphoblastic Leukaemia (more common in older adults)
- 50% are asymptomatic
- Hepaosplenomegaly
- Lymphadenopathy
Chronic Myelogenous Leukaemia
- 20% are asymptomatic
- Splenomegaly

Investigations

Bone marrow aspirate
Bone marrow biopsy
Cytogenetic testing
Flow cytometry with immunophenotyping
Molecular testing
Peripheral smear

Treatment

A patient with suspected leukemia should be referred to a hematologist-oncologist to confirm the diagnosis and initiate treatment.
Treatment depends on type of leukaemia

References

Gbenjo JTC, McCrary GLM, Wilson SE. Leukemia: what primary care physicians need to know. Am Fam Physician. 2023;107(4):397-405.
Inaba H, Greaves M, Mullighan CG. Acute lymphoblastic leukaemia. Lancet. 2013;381(9881):1943-1955. doi:10.1016/S0140-6736(12)62187-4.
Döhner H, Wei AH, Appelbaum FR, Craddock C, DiNardo CD, Dombret H, et al. Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN. Blood. 2022;140(12):1345-1377. doi:10.1182/blood.2022016867.
Hallek M, Cheson BD, Catovsky D, Caligaris-Cappio F, Dighiero G, Döhner H, et al. iwCLL guidelines for diagnosis, indications for treatment, response assessment, and supportive management of CLL. Blood. 2018;131(25):2745-2760. doi:10.1182/blood-2017-09-806398.
Jabbour E, Kantarjian H. Chronic myeloid leukemia: 2020 update on diagnosis, therapy and monitoring. Am J Hematol. 2020;95(6):691-709. doi:10.1002/ajh.25792.