Blast crises CML are characterized by:
**Core Concept**
Blast crises in Chronic Myeloid Leukemia (CML) occur when there is an abrupt increase in the number of immature white blood cells in the bone marrow and blood, leading to a shift in the disease's clinical and laboratory profile. This transformation is often associated with a poor prognosis and requires aggressive treatment.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of blast crises in CML. Blast cells in the bone marrow and blood indicate a failure of normal hematopoiesis and an accumulation of malignant cells. The WBC count typically increases, often with an increase in the blast percentage. This transformation is often associated with the development of additional cytogenetic abnormalities, such as the isochromosome 17q or monosomy 7.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the hallmark of a blast crisis in CML. A blast crisis is characterized by an increase in blast cells, not just any increase in WBC count.
**Option B:** This option is incorrect as it does not specifically relate to the pathophysiology of blast crises in CML. While anemia can be a feature of CML, it is not a defining characteristic of a blast crisis.
**Option C:** This option is incorrect as it describes a feature of the chronic phase of CML, not a blast crisis. The WBC count in a blast crisis is typically much higher than in the chronic phase.
**Clinical Pearl / High-Yield Fact**
In the context of CML, a blast crisis is a medical emergency requiring immediate intervention. The presence of blast cells in the blood or bone marrow necessitates a change in treatment strategy, often involving chemotherapy, targeted therapy, or stem cell transplantation.
**Correct Answer: C.**