Blast crisis may be discovered incidentally on full blood count or when assessing patients with symptoms and signs such as fever, fatigue, malaise, weight loss, anaemia, thrombocytopenia, or splenomegaly.
Full blood count with differential is the initial laboratory test. Cytopenias and the presence of blast cells serve as clues to diagnosis. These should lead to a peripheral blood smear and bone marrow examination.
Diagnosis is usually confirmed by the percentage of blast cells (e.g., ≥20% [World Health Organization criteria] or ≥30% [MD Anderson Cancer Center and the International Bone Marrow Transplant Registry criteria]) in the peripheral blood or bone marrow. Diagnosis of CML requires the presence of the Philadelphia chromosome (a genetic mutation that results in the oncogenic BCR-ABL fusion gene).
Tyrosine kinase inhibitors are paramount in treatment. Allogeneic stem cell transplant must follow due to rapid relapse.
Blast crisis refers to the transformation of CML from the chronic or accelerated phase to blast phase.
The blast phase of CML is diagnosed by the percentage of blast cells in the peripheral blood or bone marrow, or the presence of an extramedullary accumulation of blast cells, or large foci or clusters of blasts in the bone marrow biopsy.
CML is defined by the presence of the Philadelphia chromosome.
History and exam
Key diagnostic factors
- night sweats
- abnormal/excessive bleeding
- bone pain
Other diagnostic factors
- weight loss
- petechiae, ecchymoses, or easy bruising
- abdominal pain
- visual changes
- focal neurological signs
- confusion or stupor
- history of chronic myeloid leukaemia (CML)
- exposure to alkylating chemotherapeutic agents
- exposure to ionising radiation
1st investigations to order
- FBC and differential
Investigations to consider
- peripheral blood smear
- bone marrow aspiration and biopsy
- fluorescence in situ hybridisation
- quantitative reverse-transcriptase polymerase chain reaction
- flow cytometry
- T315I gene mutation analysis
- HLA1 testing
- serum leukocyte alkaline phosphatase
- serum vitamin B12
lymphoid blast crisis
myeloid blast crisis
biphenotypic blast crisis
suboptimal response to initial treatment
partial haematological response or second chronic phase
transplant failure or recurrence post-transplant
- Organ-specific or systemic infection (bacterial, fungal, viral)
- Leukemoid reaction
- Essential thrombocythaemia
- Chronic myeloid leukemia
- Guideline on the diagnosis and management of chronic myeloid leukaemia
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