Acute myeloid leukaemia
- Lesion
Immature myeloid cells fill the marrow within weeks, causing anaemia, infections and bleeding. Genetics decide the name and the outlook.
What it is
Acute myeloid leukaemia (AML) is a neoplasm of myeloid progenitors whose differentiation is blocked, so blasts accumulate and replace the marrow. It affects mainly adults and becomes more common with age. AML is now classified first by its genetic lesion; the classic balanced translocations of younger patients carry a better prognosis, whereas AML after myelodysplasia or prior chemotherapy, and AML with TP53 mutations, do badly. Blasts usually make up at least 20% of marrow cells, but defining genetic lesions allow the diagnosis with fewer.
Structure
- Marrow: packed with blasts, few normal precursors.
- Myeloblasts: fine chromatin, two to four nucleoli, more cytoplasm than lymphoblasts, fine azurophilic granules, Auer rods.
- Monoblasts: folded or lobulated nuclei, grey cytoplasm, no Auer rods.
- Blood: blast counts vary widely; some patients have no circulating blasts (aleukaemic leukaemia).
Step by step
- A class of mutations disrupts myeloid transcription factors (RUNX1, CBFB, RARA, CEBPA) and blocks maturation.
- A second class activates growth signalling (FLT3, KIT, RAS), driving proliferation.
- Epigenetic mutations (DNMT3A, TET2, IDH1/IDH2) often came first, as clonal haematopoiesis.
- Blasts replace normal haematopoiesis: anaemia, neutropenia and thrombocytopenia.
- Blasts may infiltrate gums, skin, CNS or form a myeloid sarcoma; some types trigger DIC.
Genetic groups of AML to know
| Lesion | Genes | Morphology clue | Prognosis |
|---|---|---|---|
| t(8;21) | RUNX1::RUNX1T1 | Maturing granulocytes, Auer rods | Favourable |
| inv(16) | CBFB::MYH11 | Myelomonocytic cells with abnormal eosinophils | Favourable |
| t(15;17) | PML::RARA | Abnormal promyelocytes, many Auer rods, DIC | Very good with retinoic acid and arsenic |
| NPM1 mutation (without FLT3-ITD) | NPM1 | Often monocytic, normal karyotype | Favourable |
| TP53 mutation, complex karyotype, myelodysplasia-related | TP53, others | Multilineage dysplasia, often older or after therapy | Poor |
Markers
- MPO
- CD33
- CD13
- CD117
- CD34
- CD14 and CD64 (monocytic)
Clinical notes
- Weeks of fatigue, fever, infections (often fungal and Pseudomonas), mucosal bleeding and petechiae.
- A pancytopenic patient needs a marrow examination, because blasts may be absent from the blood.
- Inhibitors of mutated IDH or FLT3 and BCL2 inhibitors have joined chemotherapy and transplantation.
Test yourself
Think of the answer, then tap the question to see it.
What are Auer rods and what do they mean?
Needle-shaped aggregates of azurophilic granules in the cytoplasm of blasts; they identify the blasts as myeloid.
Which AML lesions carry a favourable prognosis?
t(8;21), inv(16), t(15;17) and NPM1 mutation without FLT3-ITD.
Which AML types infiltrate the gums and skin?
AML with monocytic differentiation.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Acute Myeloid Leukemia Treatment (PDQ®)–Patient Version (National Cancer Institute (NCI), 2026); Core binding factor acute myeloid leukemia: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.