What does blast crisis signify in chronic myeloid leukemia?

• A. Acute transformation to an acute leukemia with high blasts
• B. Remission with normal blood counts
• C. Chronic phase with low blasts
• D. Transformation to lymphoma

Answer: (A)

Blast crisis signifies progression of chronic myeloid leukemia into an acute leukemic phase. In this stage, there is a marked increase in blasts in the bone marrow and/or peripheral blood, typically 20% or more, which defines acute leukemia (AML or ALL) in the setting of CML. This transition marks a shift from the slow, chronic phase to a rapidly advancing disease with symptoms like fatigue, anemia, infections, bleeding, and organ enlargement. It reflects disease evolution and often resistance to prior therapy, requiring more intensive treatment similar to acute leukemia regimens and consideration of stem cell transplantation. It is not remission, not the chronic phase with low blasts, and not transformation to lymphoma, which are different states.