Chronic myeloid leukemia

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Chronic myeloid leukaemia, abbreviated CML, is a type of myeloproliferative neoplasm. It is also known as chronic myelogenous leukemia.

It is driven by the bcr-abl fusion protein, detectable cytogenetically as the Philadelphia chromosome. It is a leukemia in that the fusion protein drives granulopoiesis (and less commonly megakaryopoiesis), resulting in marked peripheral blood leucocytosis.

General

  • Adults - usually 50s or 60s.

Clinical - commonly:[1]

  • Leukocytosis - neutrophils, myelocytes, metamyelocytes, +/-eosinophilia, +/-basophilia.

Progression:

  1. Chronic phase - potentially curable.
  2. Accelerated phase.
  3. Blast crisis.

Treatment:

Notes:

  • Myeloblast (common granulocyte precursor) -> promyelocyte -> metamyelocyte -> myelocyte -> band -> mature myelocyte.[2]

Microscopic

Features:

  • Bone marrow with too many granulocytes/granulocyte precursors.
    • Granulocyte precursors:[2]
      1. Myeloblast (common granulocyte precursor) ~ 90% nucleus, multiple nucleoli.
        • Should be less than 10%.
      2. Promyelocyte (committed to a specific linage (neutrophil, basophil or eosinophil)) - dia. 2x mature, 40-50% nucleus, one nucleolus.
      3. Metamyelocyte - dia. 2x mature, 30-40% nucleus, no nucleolus.
      4. Myelocyte - dia. 1x mature, 50-60% nucleus - kidney bean shape, no nucleolus.
      5. Band - dia. 1x mature, 30-40% nucleus - C shape/irregular, no nucleolus.

IHC

Rarely required. CML may transform into a blast phase, typically myeloid blasts, but lymphoblasts may also be seen. These blasts are typically CD34 and/or CD117 positive. The myeloid blasts will express myeloid markers and the lymphoblasts will shows lymphoid markers.

Molecular

  • t(9;22) BCR-ABL - required for diagnosis.
    • May be found in other leukemias.

See also

References

  1. Mitchell, Richard; Kumar, Vinay; Fausto, Nelson; Abbas, Abul K.; Aster, Jon (2011). Pocket Companion to Robbins & Cotran Pathologic Basis of Disease (8th ed.). Elsevier Saunders. pp. 336. ISBN 978-1416054542.
  2. 2.0 2.1 URL: http://commons.wikimedia.org/wiki/File:Hematopoiesis_%28human%29_diagram.png. Accessed on: 14 January 2012.