Chronic Myelogenous Leukemia (CML): The Daily PANCE Blueprint

The answer is  D. 20% or more blasts in the peripheral blood or bone marrow

The blast crisis phase of chronic myelogenous leukemia (CML) is characterized by a significant increase in blast cells, accounting for 20% or more of the total cells in the peripheral blood or bone marrow. This phase resembles acute leukemia and indicates a transformation to a more aggressive disease state. Patients in blast crisis typically present with symptoms such as severe anemia, bleeding tendencies, and increased susceptibility to infections due to the rapid proliferation of immature leukemic cells. The blast crisis phase signifies a poor prognosis and often necessitates more intensive treatment strategies, including potential bone marrow transplantation.

Incorrect Answers:

• A. Presence of 10% blasts in the peripheral blood: This finding is indicative of the accelerated phase of CML rather than the blast crisis. The accelerated phase is a transitional phase between the chronic phase and blast crisis and involves an increased percentage of blasts, but not reaching 20%.
• B. Increased basophils in the peripheral blood: Increased basophils are commonly observed in the accelerated phase of CML but are not a defining characteristic of the blast crisis phase. The presence of basophilia can indicate disease progression but does not specifically diagnose blast crisis.
• C. Presence of BCR-ABL1 fusion gene: The BCR-ABL1 fusion gene is present in all phases of CML, including the chronic, accelerated, and blast crisis phases. While it is a diagnostic marker for CML, it does not differentiate between the phases of the disease.
• E. Low leukocyte alkaline phosphatase (LAP) score: A low LAP score is a feature of CML in general and is not specific to the blast crisis phase. It is often used as a diagnostic tool for distinguishing CML from other causes of leukocytosis, but it does not indicate the transition to blast crisis.