Blast crisis in chronic myeloid leukemia is equivalent to which disease state?

• A. Acute leukemia
• B. Chronic infection
• C. Chronic phase
• D. Remission

Answer: (A)

Blast crisis represents a transformation of chronic myeloid leukemia into an acute leukemia–like state. In this phase, the marrow and blood are flooded with blasts (typically 20% or more), mirroring the biology and clinical behavior of acute myeloid or acute lymphoblastic leukemia. This rapid, high-blast burden drives swift marrow failure, with symptoms such as anemia, bleeding, infections, and organomegaly, and it requires urgent, intensive therapy aimed at eradicating blasts, just like treatment for acute leukemia. Because of this abrupt shift to an aggressive, acute disease, the prognosis is generally poor and options often include AML- or ALL-type induction regimens and consideration of stem cell transplantation.

Other states don’t fit this pattern: a chronic infection is unrelated to leukemic burden, the chronic phase is a slower, less aggressive period of CML, and remission implies control or disappearance of disease activity rather than the sudden blast-dominated failure seen in blast crisis.