Overview
When Blasts Take over the Marrow
Acute myeloid leukaemia (AML) is a clonal malignancy in which immature myeloid precursors, called blasts, multiply rapidly and fail to mature into functioning blood cells.
Acute myeloid leukaemia (AML) is a clonal malignancy in which immature myeloid precursors, called blasts, multiply rapidly and fail to mature into functioning blood cells. As blasts crowd the bone marrow, normal production of erythrocytes, platelets, and mature leukocytes falls. That single mechanism explains the apparently unrelated presentation. Reduced erythrocytes cause fatigue, pallor, dizziness, and exertional dyspnoea. Reduced platelets cause petechiae, gingival bleeding, epistaxis, bruising, haematuria, or gastrointestinal bleeding. Reduced functional neutrophils increase the risk of serious infection, even when the total white-cell count is normal or high. A high white-cell count does not mean the patient has adequate immune defence; circulating blasts may be numerous but ineffective. AML can also produce complications outside the marrow. A very high blast burden can impair microvascular flow, producing leukostasis. The patient may develop hypoxaemia, respiratory distress, headache, confusion, visual changes, focal neurologic deficits, or other signs of tissue hypoperfusion. Hyperleukocytosis is generally defined as a white-cell count above 100 × 10⁹/L, but symptoms determine urgency: a patient with clinical leukostasis needs emergency action rather than routine laboratory follow-up. The nurse’s first mental...
