Blast crisis

Blast Crisis

Blast crisis is a phase of chronic myeloid leukemia (CML) characterized by an aggressive increase in the number of immature white blood cells, known as blasts, in the bone marrow and blood. This phase represents the transformation of CML from a chronic phase to an acute leukemia, often resembling acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL).

Pathophysiology

Blast crisis occurs when there is a significant increase in the proliferation of leukemic blasts, which fail to differentiate into mature blood cells. This is often due to additional genetic mutations that occur in the leukemic cells, on top of the Philadelphia chromosome translocation (t(9;22)(q34;q11)) that is characteristic of CML. These additional mutations can include alterations in genes such as p53, RAS, and others that regulate cell cycle and apoptosis.

Clinical Presentation

Patients in blast crisis may present with symptoms such as:

• Fatigue
• Fever
• Weight loss
• Bone pain
• Splenomegaly
• Bleeding and bruising due to thrombocytopenia
• Infections due to neutropenia

Diagnosis

The diagnosis of blast crisis is made when the percentage of blasts in the blood or bone marrow exceeds 20%. This is determined through:

• Complete blood count (CBC)
• Bone marrow biopsy
• Cytogenetic analysis to identify additional chromosomal abnormalities

Treatment

Treatment options for blast crisis are limited and often involve:

• Tyrosine kinase inhibitors (TKIs) such as imatinib, dasatinib, or nilotinib
• Chemotherapy regimens similar to those used for AML or ALL
• Hematopoietic stem cell transplantation (HSCT) for eligible patients

Prognosis

The prognosis for patients in blast crisis is generally poor, with a median survival of only a few months without aggressive treatment. The response to therapy is often limited, and the disease is typically resistant to standard treatments used in the chronic phase of CML.

See Also

• Chronic myeloid leukemia
• Acute myeloid leukemia
• Acute lymphoblastic leukemia