The blast cells of acute lymphocytic leukemia in childhood contain
**Core Concept**
Acute lymphocytic leukemia (ALL) is a type of cancer characterized by the uncontrolled proliferation of lymphoid blast cells in the bone marrow. In childhood ALL, the blast cells are typically of B-cell or T-cell origin, and their morphology and immunophenotype are crucial for diagnosis.
**Why the Correct Answer is Right**
The correct answer is related to the specific immunophenotypic markers expressed on the surface of lymphoid blast cells in childhood ALL. These cells typically express CD19, CD20, and CD22, which are specific markers for B-cell lineage. In contrast, T-cell lineage ALL cells express CD2, CD3, and CD7. The presence of these markers is essential for distinguishing ALL from other types of leukemia and for guiding treatment decisions.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct immunophenotypic markers for B-cell lineage ALL. While CD19 is a correct marker, CD10 is not exclusive to ALL and can be expressed in other conditions.
**Option B:** This option is incorrect because it does not accurately represent the typical immunophenotypic profile of childhood ALL. While CD20 is a correct marker, CD56 is more commonly associated with natural killer (NK) cell lineage.
**Option C:** This option is incorrect because it does not accurately represent the typical immunophenotypic profile of childhood ALL. While CD7 is a correct marker for T-cell lineage, CD4 and CD8 are more commonly associated with mature T-cell populations.
**Clinical Pearl / High-Yield Fact**
It is essential to note that childhood ALL is characterized by a distinct immunophenotypic profile, which can be used to guide treatment decisions and monitor response to therapy.
**Correct Answer: C. CD19, CD20, CD22**