Leukaemia: Acute and Chronic

Key points

• • Leukaemia is a malignant clonal disorder of the blood-forming cells of the bone marrow; it is classified by speed (acute or chronic) and by cell line (myeloid or lymphoid).
• • Acute leukaemias are made of immature blast cells, come on quickly, and cause marrow failure with anaemia, infections and bleeding as normal cells are crowded out.
• • Chronic leukaemias are made of more mature-looking cells, come on slowly, and may be found by chance on a blood count before symptoms appear.
• • Acute lymphoblastic leukaemia is mainly a disease of children, while acute myeloid leukaemia is commoner in adults and can show Auer rods in the blast cells.
• • Chronic myeloid leukaemia is linked with the Philadelphia chromosome, a swap between chromosomes 9 and 22 that creates the BCR-ABL fusion gene.
• • Chronic lymphocytic leukaemia is a disease of older adults in which small mature lymphocytes accumulate, and fragile smudge cells are seen on the blood film.