A 6-year-old boy presents with pallor, petechiae, and bone pain. Peripheral blood shows 80% lymphoblasts. Flow cytometry shows CD19+, CD10+, TdT+, and CD33−. Cytogenetics reveal hyperdiploidy with >50 chromosomes. Which statement about this karyotype is correct?
- A It is the most common favorable-risk cytogenetic abnormality in pediatric B-ALL ✓
- B It confers a poor prognosis requiring immediate hematopoietic stem cell transplant
- C It is associated with t(12;21) ETV6-RUNX1 fusion
- D It is equivalent to Philadelphia chromosome positivity
Correct answer: A. It is the most common favorable-risk cytogenetic abnormality in pediatric B-ALL
Explanation
Hyperdiploidy (>50 chromosomes) is the most common cytogenetic abnormality in childhood A-ALL and is a favorable prognostic factor, associated with excellent outcomes with standard chemotherapy. t(12;21) ETV6-RUNX1 is a separate favorable abnormality that can coexist with hyperdiploidy but is not identical to it. Philadelphia chromosome (t(9;22)) confers poor risk and requires tyrosine kinase inhibitor therapy. Transplant is not indicated for hyperdiploid ALL in first remission.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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