Haematology & Oncology

Acute Lymphoblastic Leukaemia (ALL)

A maturation arrest in the lymphoid lineage lets lymphoblasts proliferate and fill the marrow, causing rapid marrow failure plus a distinctive tendency to infiltrate the central nervous system and testes; it is the commonest childhood cancer.

In a nutshell

ALL is a lymphoid maturation arrest: lymphoblasts (no Auer rods) fill the marrow, causing rapid marrow failure, and characteristically seed the central nervous system and testes. It is the commonest childhood cancer, peaking between two and five years. The Philadelphia chromosome marks higher-risk disease and adds a tyrosine kinase inhibitor.

Classic presentation

A young child with a few weeks of pallor, fatigue, fever, bruising and bone pain or a limp, with lymphoblasts on the blood film.

Key points

ALL is defined by 20% or more lymphoblasts; lineage (B or T) is set by immunophenotyping, and there are no Auer rods.
It is the commonest childhood cancer, peaking at two to five years, and is associated with Down syndrome.
Bone pain, a limp, lymphadenopathy and hepatosplenomegaly are common; T-cell disease can present with a mediastinal mass.
The central nervous system and testes are sanctuary sites, so treatment always includes CNS-directed (intrathecal) therapy.
Test every case for the Philadelphia chromosome (BCR-ABL1): it marks higher risk and adds a tyrosine kinase inhibitor to chemotherapy.

First-line investigation

Urgent full blood count and blood film for cytopenias and lymphoblasts, then bone marrow biopsy with immunophenotyping and cytogenetics, plus a lumbar puncture to assess CNS involvement.

Management

Stabilise acute presentation

Escalate same day for suspected acute leukaemia, sepsis, bleeding, neurological compromise or a symptomatic mediastinal mass.^3,1,2

Confirm lineage and risk

Use marrow morphology, flow cytometry, cytogenetics, molecular testing and baseline complication assessment through the specialist service.^1,2

Deliver protocol-based treatment

Use multi-phase induction, consolidation or intensification and maintenance with CNS-directed therapy; follow the current UK protocol and BNF.^10,2,9

Adapt for genetics and relapse

Use MRD and BCR::ABL1 status to adapt treatment; selected relapsed B-cell disease may access immunotherapy, TKIs or cellular therapy under NICE criteria.^4,5,6,7

Prevent treatment complications

Plan tumour-lysis prevention, infection and neutropenic-sepsis pathways, transfusion support, fertility preservation and late-effect care.^8,1,9

Monitor MRD and survivorship

Follow MRD, relapse, treatment toxicity, endocrine and fertility effects, second malignancy and psychosocial needs.^1,2

Exam traps

No Auer rods in ALL: Auer rods indicate myeloid lineage (AML).
Bone pain or a limp in a pale, bruising child is a classic ALL presentation, not simply a musculoskeletal problem.
Treatment always covers the central nervous system even when the marrow is in remission, because the CNS is a sanctuary site.
The white cell count can be normal or low; blasts on the film, not a high count, make the diagnosis.

Illustrations

Blood film in acute lymphoblastic leukaemiaPeripheral blood film showing lymphoblasts with a high nuclear-to-cytoplasmic ratio and no Auer rods.Animalculist, Wikimedia Commons · CC-BY-SA-4.0

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.