Acute Myeloid Leukaemia

Overview – Acute Myeloid Leukaemia

Acute Myeloid Leukaemia (AML) is an aggressive malignancy of myeloid progenitor cells (myeloblasts), leading to uncontrolled proliferation, bone marrow failure, and systemic symptoms. It is most common in adults, especially the elderly, and carries a poorer prognosis than ALL. Rapid diagnosis and initiation of chemotherapy are essential for survival.

Definition

  • Malignant clonal disorder of myeloblasts
  • Leads to bone marrow failure and widespread infiltration of tissues
  • Characterised by >20% myeloblasts in bone marrow or peripheral blood

Aetiology

  • De novo AML: No preceding haematological disorder
  • Secondary AML: Progression from:
  • Risk factors:
    • Radiation exposure
    • Benzene, smoking
    • Genetic syndromes (e.g. Down syndrome)

Pathophysiology

  • Genetic mutations in myeloid stem cells →
    • Arrested maturation
    • Accumulation of immature myeloblasts
    • Suppression of normal haematopoiesis → Anaemia, thrombocytopenia, neutropenia
  • Infiltration into liver, spleen, lymph nodes, gums, and CNS

Clinical Features

  • Demographics: Most common in older adults
  • Symptoms:
    • Bone pain (especially sternum)
    • Constitutional symptoms (fatigue, weight loss)
    • Anaemia → pallor, dyspnoea
    • Thrombocytopenia → easy bruising, bleeding
    • Neutropenia → frequent infections
    • Gum hypertrophy (especially monocytic AML subtypes)
  • Signs:
    • Hepatosplenomegaly
    • Lymphadenopathy
    • Fever
    • Petechiae, mucosal bleeding

Investigations

  • FBC:
    • Anaemia (↓ Hb), Thrombocytopenia (↓ Plts), ↑ or ↓ WCC
    • Circulating blast cells
  • Blood film:
    • Myeloblasts, possibly with Auer rods (pathognomonic)
  • Bone marrow biopsy:
    • 20% blasts required for diagnosis
    • Confirm presence of Auer rods
  • Cytogenetics:
    • Determines prognosis and treatment strategy
    • Favourable: t(8;21), inv(16), t(15;17)
  • Cytochemistry:
    • Myeloperoxidase and Sudan Black → Positive in AML (Negative in ALL)
  • CXR/CT:
    • Evaluate for mediastinal mass, lymphadenopathy, or infection
ACUTE MYELOID LEUKAEMIA
Myeloblasts with Auer rods seen in Acute Myeloid Leukemia (AML), advanced stage. Bone Marrow: Paulo Henrique Orlandi Mourao, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Management

  • Supportive care:
    • Blood and platelet transfusions
    • Antibiotics, antivirals, antifungals
    • Tumour lysis syndrome prophylaxis (hydration, allopurinol)
  • Chemotherapy:
    • Induction: “7+3” regimen (cytarabine + anthracycline)
    • Consolidation: high-dose cytarabine or stem cell transplant
  • Allogeneic stem cell transplant:
    • Curative potential for high-risk or relapsed patients

Prognosis

  • Poorer than ALL
  • Mortality increases with age
  • Prognostic factors include:
    • Cytogenetics
    • Age
    • Response to induction therapy

Summary – Acute Myeloid Leukaemia

Acute Myeloid Leukaemia (AML) is a life-threatening malignancy of myeloblasts, often presenting with bone marrow failure and systemic signs. Diagnosis relies on blood film, bone marrow biopsy, and cytogenetics. Prompt treatment with chemotherapy and possible stem cell transplant is crucial. For more haematological topics, refer to our Blood & Haematology Overview page.

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