A 4-year-old girl presents with a 3-week history of pallor, progressive fatigue, and multiple ecchymoses. CBC shows: Hb 5.2 g/dL, WBC 85,000/mm³ (90% blasts), platelets 18,000/mm³. Bone marrow examination reveals >80% lymphoblasts; immunophenotyping shows CD10+, CD19+, CD22+, terminal deoxynucleotidyl transferase (TdT)+, CD34+. Cytogenetics shows t(12;21)(p13;q22). What is the prognostic implication of this cytogenetic finding?

• A Poor prognosis; associated with Ph-like ALL requiring TKI therapy
• B Intermediate prognosis; requires MRD-guided intensification
• C Poor prognosis; associated with early relapse and CNS disease
• D Favorable prognosis; ETV6-RUNX1 fusion is the most common translocation in childhood B-ALL ✓

Explanation

The t(12;21)(p13;q22) translocation creates the ETV6-RUNX1 (TEL-AML1) fusion gene and is the most common chromosomal translocation in childhood B-cell ALL, occurring in approximately 20–25% of cases. It confers a favorable prognosis with 5-year event-free survival rates exceeding 90% with standard therapy. The translocation is cryptic (not visible on standard karyotype) and requires FISH or RT-PCR for detection. Philadelphia chromosome t(9;22) and BCR-ABL1, hypodiploidy (<44 chromosomes), and MLL rearrangements are associated with poor prognosis in pediatric ALL.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.