Blast crisis

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Last reviewed: 14 Jun 2025

Last updated: 29 Nov 2024

Blast crisis may be discovered incidentally on complete blood count or when assessing patients with symptoms and signs such as fever, fatigue, malaise, weight loss, anemia, thrombocytopenia, or splenomegaly.

Complete 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 confirmed by the percentage of blast cells in the peripheral blood and/or bone marrow (i.e., ≥20% or ≥30% depending on the criteria used) or the presence of an extramedullary proliferation of blasts.

Diagnosis of chronic myeloid leukemia (CML) requires the presence of the Philadelphia chromosome (a genetic mutation that results in the oncogenic BCR::ABL1 fusion gene).

Tyrosine kinase inhibitors are paramount in treatment, often used in combination with chemotherapy. Allogeneic stem cell transplant must follow due to rapid relapse.

Definition

Blast crisis refers to the transformation of CML from the chronic or accelerated phase to the blast phase.

The blast phase of CML is diagnosed by the percentage of blast cells in the peripheral blood and/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.[1][2]

CML is defined by the presence of the Philadelphia chromosome.[3]

History and exam

Key diagnostic factors

splenomegaly
fatigue
malaise
night sweats
fever
abnormal/excessive bleeding
bone pain

Full details

Other diagnostic factors

weight loss
petechiae, ecchymoses, or easy bruising
infection
abdominal pain
visual changes
focal neurologic signs
priapism
tinnitus
confusion or stupor

Full details

Risk factors

history of chronic myeloid leukemia (CML)
exposure to alkylating chemotherapeutic agents
exposure to ionizing radiation

Full details

Diagnostic tests

1st tests to order

CBC and differential

Full details

Tests to consider

peripheral blood smear
bone marrow aspiration and biopsy for cytogenetic analysis
quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR)
fluorescence in situ hybridization
flow cytometry
mutational analysis
HLA1 testing
lumbar puncture
serum leukocyte alkaline phosphatase
serum vitamin B12

Full details

Treatment algorithm

ACUTE

lymphoid blast crisis

myeloid blast crisis

biphenotypic blast crisis

ONGOING

suboptimal response to initial treatment

partial hematologic response or second chronic phase

transplant failure or recurrence posttransplant

Contributors

Authors

Carlos Palacio, MD, MPH, FACP

Professor of Medicine

University of Florida College of Medicine

Jacksonville

Disclosures

CP declares that he has no competing interests.

Marwan E. Shaikh, MD

Assistant Professor

College of Medicine

Division of Hematology and Oncology

Mayo Clinic Jacksonville

Jacksonville

Disclosures

MES declares that he has no competing interests.

Acknowledgements

Dr Carlos Palacio and Dr Marwan E. Shaikh would like to gratefully acknowledge Fauzia Rana, a previous contributor to this topic.

Disclosures

FR declares that she has no competing interests.

Peer reviewers

Danilo Perrotti, MD, PhD

Assistant Professor of Human Cancer Genetics

Ohio State University

Columbus

Disclosures

DP declares that he has no competing interests.

References

Our in-house evidence and editorial teams collaborate with international expert contributors and peer reviewers to ensure that we provide access to the most clinically relevant information possible.

Key articles

National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: chronic myeloid leukemia [internet publication].Full text

Smith G, Apperley J, Milojkovic D, et al; British Society for Haematology. A British Society for Haematology guideline on the diagnosis and management of chronic myeloid leukaemia. Br J Haematol. 2020 Oct;191(2):171-93.Full text Abstract

Hochhaus A, Saussele S, Rosti G, et al; ESMO Guidelines Committee. Chronic myeloid leukaemia: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol. 2017 Jul 1;28(suppl 4):iv41-51.Full text Abstract

Hochhaus A, Baccarani M, Silver RT, et al. European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia. Leukemia. 2020 Apr;34(4):966-84.Full text Abstract

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials
- Organ-specific or systemic infection (bacterial, fungal, viral)
- Leukemoid reaction
- Essential thrombocythemia
More Differentials
Guidelines
- Chronic myeloid leukemia
- NCCN clinical practice guidelines in oncology: hematopoietic cell transplantation (HCT)
More Guidelines
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Blast crisis

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic tests

1st tests to order

Tests to consider

Treatment algorithm

lymphoid blast crisis

myeloid blast crisis

biphenotypic blast crisis

suboptimal response to initial treatment

partial hematologic response or second chronic phase

transplant failure or recurrence posttransplant

Contributors

Authors

Carlos Palacio, MD, MPH, FACP

Disclosures

Marwan E. Shaikh, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Danilo Perrotti, MD, PhD

Disclosures

References

Key articles

Reference articles

A full list of sources referenced in this topic is available to users with access to all of BMJ Best Practice.

Differentials

Guidelines

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice