Chronic and myeloid disorders

Chronic myeloid leukaemia

Overview

Myeloproliferative neoplasm driven by BCR::ABL1, progressing through chronic, accelerated and blast phases if uncontrolled.

  • Caused by the Philadelphia chromosome t(9;22) (BCR::ABL1) (1).
  • Untreated: chronic phase (indolent, may last 5-6 years), accelerated phase (worsening anaemia, thrombocytopenia or thrombocytosis, splenomegaly, clonal evolution, rising basophils, blasts up to 19%) then blast phase (1).
Presentation

Often incidental leucocytosis; fatigue, weight loss, night sweats, early satiety or splenomegaly. Film shows granulocytic left shift and basophilia.

  • Early "benign" stage is nonspecific (malaise, anorexia, weight loss). Accelerated/blast phases bring splenomegaly, pallor, bruising/bleeding, fever, lymphadenopathy and skin changes (1).
  • Film shows immature granulocytes, basophilia and eosinophilia, which helps distinguish CML from reactive leucocytosis such as infection (1).
Urgent features

Leucostasis symptoms, blast transformation, severe splenic pain/infarction or tumour lysis requires urgent haematology assessment.

  • Blast phase behaves like acute leukaemia and needs specialist-led therapy, sometimes with TKI plus chemotherapy and allogeneic transplant (1).
Diagnosis

FBC/film, marrow assessment and demonstration of BCR::ABL1 by molecular/cytogenetic testing.

  • Diagnosis: peripheral smear, bone marrow aspirate and demonstration of the Philadelphia chromosome (1). Differential: other myeloproliferative neoplasms and reactive leucocytosis.
Management

Tyrosine-kinase inhibitor therapy with serial molecular monitoring. Adherence, interactions and cardiovascular/metabolic adverse effects are important. Transplant is reserved for selected resistant or advanced disease.

  • In chronic phase, TKIs (imatinib, nilotinib, dasatinib, bosutinib, ponatinib) are the initial treatment; they are very effective but not curative (1). Allogeneic stem cell transplant is reserved for TKI failure or progression to accelerated/blast phase (1).
References
  1. Merck Manual Professional: Chronic myeloid leukemia (CML)

Last updated from Sen’s notes on 9 October 2026.