Chronic myeloid leukemia

Big picture

Chronic myeloid leukemia (CML) is the classic Philadelphia chromosome-positive chronic myeloproliferative neoplasm. The whole topic is built around one molecular event:

t(9;22) → BCR::ABL1 fusion gene → constitutively active tyrosine kinase → uncontrolled granulocytic proliferation.

For the exam, recognize CML by:

Marked leukocytosis
+ full spectrum of granulocyte maturation in peripheral blood
+ basophilia/eosinophilia
+ splenomegaly
+ Philadelphia chromosome / BCR::ABL1 positivity

The textbook describes CML as a rare chronic myeloproliferative neoplasm with incidence about 1–2/100,000/year, usually diagnosed in older adults, with a slight mal