A 28-year-old man presents with gum bleeding and petechiae. Hemoglobin is 8.2 g/dL, platelet count 18,000/µL, WBC 2,100/µL. Peripheral smear shows abnormal promyelocytes with bilobed nuclei and dense granules. PT and aPTT are prolonged, fibrinogen is 80 mg/dL, and D-dimer is markedly elevated. Which of the following is the most appropriate initial therapy?
- A Rituximab
- B Imatinib
- C All-trans retinoic acid ✓
- D Hydroxyurea
Correct answer: C. All-trans retinoic acid
Explanation
The coagulopathy with low fibrinogen and abnormal promyelocytes indicates acute promyelocytic leukemia, driven by t(15;17) forming the PML-RARA fusion transcript. The fusion protein arrests granulocytic differentiation at the promyelocyte stage and triggers tissue-factor mediated DIC. All-trans retinoic acid binds the retinoic acid receptor component and releases the differentiation block. Imatinib targets BCR-ABL1 in CML and has no role here.
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.