A 32-year-old woman presents with gum bleeding and widespread petechiae. WBC is 15,000/uL with numerous abnormal promyelocytes containing Auer rods, hemoglobin 8 g/dL, platelets 18,000/uL, fibrinogen 80 mg/dL, and markedly elevated D-dimer. Karyotyping shows t(15;17)(q24;q21). Which agent acts by inducing terminal differentiation of the malignant promyelocytes?
- A Imatinib mesylate
- B All-trans retinoic acid ✓
- C Hydroxyurea
- D Cytarabine
Correct answer: B. All-trans retinoic acid
Explanation
The PML-RARA fusion protein of acute promyelocytic leukemia arrests differentiation at the promyelocyte stage and drives DIC through tissue factor in the granules. All-trans retinoic acid binds the RARA moiety of the fusion, releases the differentiation block, and matures the blasts into neutrophils. Imatinib targets BCR-ABL1, while cytarabine and hydroxyurea are cytotoxic rather than differentiating agents.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.