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Haematology & Oncology

Acute Myeloid Leukaemia (AML)

A maturation arrest in the myeloid lineage lets myeloblasts proliferate and fill the marrow, so normal blood production collapses over days to weeks into the anaemia, infection and bleeding of marrow failure, most often in an older adult.

In a nutshell

AML is a myeloid maturation arrest: myeloblasts (sometimes with Auer rods) fill the marrow and cause rapid marrow failure, typically in an older adult. Acute promyelocytic leukaemia is the emergency subtype, causing DIC and treated with all-trans retinoic acid on suspicion.

Classic presentation

An older adult presents over days to weeks with fatigue, infection and bruising, and the blood film shows myeloblasts, some containing Auer rods.

Key points

  • AML is defined by 20% or more myeloblasts in the marrow; Auer rods on the film confirm myeloid lineage.
  • Marrow failure (anaemia, infection, bleeding) develops over days to weeks, so suspected AML is a same-day referral.
  • Gum hypertrophy and skin deposits point to monocytic subtypes; a very high blast count can cause leucostasis.
  • Acute promyelocytic leukaemia carries t(15;17)/PML-RARA, causes disseminated intravascular coagulation, and is started on all-trans retinoic acid the moment it is suspected.
  • Fit patients have intensive anthracycline plus cytarabine induction; higher-risk disease is offered allogeneic stem cell transplant.

First-line investigation

Urgent full blood count and blood film for cytopenias and myeloblasts, then bone marrow biopsy with immunophenotyping and cytogenetics (including testing for t(15;17)).

Management

Treat AML and APL as urgent

  • Escalate same day for suspected AML, especially blasts, bleeding, sepsis, leucostasis symptoms or coagulopathy.3,2

Start APL treatment on suspicion

  • In suspected APL, send rapid molecular testing and start ATRA through haematology without waiting for confirmation; support coagulopathy urgently.5,6,9

Classify and risk-stratify

  • Use marrow morphology, flow, cytogenetics and molecular tests, plus fitness and comorbidity assessment, to select treatment intensity.1,10

Induce and consolidate

  • Use current UK protocol induction, response-adapted consolidation and selected transplant; consider targeted treatment when genetics and NICE criteria support it.8,2,10

Prevent early complications

  • Use tumour-lysis, neutropenic-sepsis, transfusion, fertility and treatment-toxicity plans from the specialist service.7,2,9

Monitor response and relapse

  • Follow measurable residual disease, molecular markers where useful, late effects and relapse through the specialist MDT.1,2,4

Exam traps

  • Auer rods indicate myeloid lineage (AML), not lymphoid; they are never seen in ALL.
  • A patient with new bleeding, a low fibrinogen and promyelocytes on the film has APL: start all-trans retinoic acid before waiting for genetic confirmation.
  • The white cell count can be low in AML; blasts on the film, not a high count, make the diagnosis.
  • Do not delay for routine outpatient review: acute leukaemia progresses over days, so referral is same-day.

Illustrations

AML blood film with Auer rodsPeripheral blood film in acute myeloid leukaemia showing myeloblasts, one containing a needle-shaped Auer rod.Makysm, Wikimedia Commons · CC0
Marrow failure from blast crowdingDiagram showing myeloblasts crowding out normal haematopoiesis and producing anaemia, infection risk and bleeding in parallel.PassFinals · original

Key sources

  1. BSH: Recommendations for laboratory testing of UK patients with acute myeloid leukaemia (UK BSH guidance covering morphology, flow, cytogenetics and molecular testing.)Published 27 Oct 2022
  2. NICE NG47: Haematological cancers: improving outcomes (UK specialist diagnostic, MDT, high-intensity treatment and neutropenic-safety service recommendations.)Published 25 May 2016
  3. NICE NG12: Suspected cancer: recognition and referral (Current UK referral recommendations for suspected acute leukaemia.)Updated 15 Apr 2026
  4. NHS: Acute myeloid leukaemia (UK patient pathway describing rapid progression, testing, treatment and follow-up.)
  5. NICE TA526: Arsenic trioxide for acute promyelocytic leukaemia (NICE recommendation for arsenic trioxide with ATRA in selected APL.)Published 13 Jun 2018
  6. NHS England: Arsenic trioxide with ATRA for high-risk acute promyelocytic leukaemia (UK national commissioning guidance for high-risk APL.)
  7. BSH: Updated guidelines for the diagnosis and management of tumour lysis syndrome (Current UK tumour-lysis guidance.)Published 3 Sept 2025 | Updated 8 Dec 2025
  8. NICE TA523: Midostaurin for untreated acute myeloid leukaemia (NICE recommendation for midostaurin with intensive therapy in newly diagnosed FLT3-mutated AML.)Published 13 Jun 2018
  9. BNF online (Check current specialist AML and APL prescribing, interactions and monitoring.)
  10. BSH: Management of older patients with frailty and acute myeloid leukaemia (UK BSH guidance on fitness, frailty, treatment intensity and supportive goals.)Published 24 Aug 2022 | Updated 26 Aug 2022

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.