A 32-year-old man presents with bleeding gums and petechiae over three days. CBC: Hb 8.9 g/dL, WBC 3,400/μL with 40% abnormal promyelocytes showing bilobed nuclei and coarse granules, platelets 18,000/μL. Fibrinogen is 80 mg/dL and D-dimer is markedly elevated. Which cytogenetic abnormality defines this leukaemia?

• A t(8;21)(q22;q22)
• B t(9;22)(q34;q11)
• C inv(16)(p13;q22)
• D t(15;17)(q24;q21) ✓

Explanation

The coagulopathy with low fibrinogen plus promyelocytes indicates acute promyelocytic leukaemia, defined by t(15;17) producing PML-RARα, which blocks myeloid differentiation at the promyelocyte stage. All-trans retinoic acid binds this fusion receptor and restores differentiation. inv(16) defines core-binding factor AML-M4Eo, which presents with eosinophilia rather than DIC, and t(8;21) is another core-binding factor leukaemia without a coagulopathy phenotype.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.