Last reviewed: 24 Feb 2023
Last updated: 23 Sep 2022

This page compiles our content related to leukaemia. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.



A malignant clonal disease that develops when a B/T-precursor-stage lymphoid progenitor cell becomes genetically altered through somatic changes and undergoes uncontrolled proliferation. This progressive clonal expansion eventually leads to acute lymphocytic leukaemia (ALL), characterised by early lymphoid precursor cells replacing the normal haematopoietic cells of the bone marrow and further infiltrating various body organs. ALL can occur at any age, but is most commonly diagnosed in those aged under 20 years.[1] It accounts for 80% of leukaemias in paediatric patients and 20% in adults.[2] Clinical presentation is heterogenous and reflects the biological subtype. Most patients present with signs and symptoms associated with cytopenias. Enlarged lymph nodes are also frequently the initial prompt for the patient to seek medical attention.[3] T-lineage ALL is characterised by an older age of onset, male sex preponderance, and inferior outcome in comparison with B-ALL.[2] The cytogenetic abnormality has prognostic implications.

A cancer of B lymphocytes. Failure of B lymphocytes to undergo maturation and full differentiation leads to a monoclonal population of dysfunctional but self-renewing B lymphocytes. These lymphocytes can infiltrate lymphatic tissues and haematopoietic organs such as the liver, spleen and bone marrow. A key risk factor is age over 60 years. Lymphadenopathy, splenomegaly (in 50% of cases), shortness of breath and fatigue are key diagnostic factors.[4][5][6] It is diagnosed by full blood count (FBC) with differential, blood smear showing smudge cells, and flow cytometry.[4][5][6] Most patients are diagnosed following a routine FBC for an unrelated reason.

The clonal expansion of myeloid blasts in the bone marrow, peripheral blood, or extra-medullary tissues. Occurs predominantly in older adults.[7] Common findings are pallor, ecchymoses and petechiae. Management of acute promyelocytic leukaemia (APML), an aggressive subtype of acute myelogenous leukaemia (AML) with distinct cytological and clinical features, is distinct from that of standard AML treatment.[8]

A malignant clonal disorder of the haematopoietic stem cell that results in marked myeloid hyperplasia of the bone marrow.[9] Incidence peaks between the ages of 65 and 74 years, median age at diagnosis is 65 years.[10] The only known risk is exposure to ionising radiation.[11] Possible symptoms include fever, chills, malaise, weight loss, abdominal discomfort, and night sweats, but approximately one third of patients are asymptomatic. Nearly all patients have elevated white blood cell counts and around 75% of patients have splenomegaly.[12] Diagnosis should be confirmed by the presence of the Philadelphia chromosome and/or the BCR-ABL1 transcripts in peripheral blood or bone marrow cells.[13][14]

Blast crisis refers to the transformation of chronic myelogenous leukaemia (CML) from the chronic or accelerated phase to the blast phase. The blast phase is defined as the presence of ≥30% myeloblasts in the blood, bone marrow, or both, or the presence of extramedullary disease (International Bone Marrow Transplant Registry criteria).[14] Anaemia, infections, abnormal bleeding, bone pain, and constitutional symptoms (night sweats, weight loss, fever, fatigue) are common presenting complaints of blast-phase CML. The treatment goal is to achieve a complete haematological remission or at least return to the chronic phase in order to perform stem cell transplant.

A B-cell malignancy commonly characterised by symptoms of fatigue, a markedly enlarged spleen, and a distinctive histological appearance on peripheral blood smear (B-cells with delicate cytoplasmic projections resembling hair) and bone marrow biopsy. Hairy cell leukaemia (HCL) is relatively uncommon, with marked geographic variation in frequency. The median age at occurence is 50 years; HCL affects more men than women.[15] It often presents with abdominal discomfort or fullness. This is attributed to splenomegaly, which is present in around 60% to 90% of patients.[15][16] The disease is not curable. However, it is highly responsive to therapy and may be managed successfully for a decade or more.

Leukaemias may cause pancytopenia through decreased production, or increased destruction or sequestration, of blood cells.

Leukaemias are a cause of acquired neutropenia, accounting for some of the typical symptoms e.g., recurrent infections.



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