A 70-year-old man presents with fatigue and splenomegaly. CBC: WBC 22,000/μL with left shift, Hb 10 g/dL, platelets 650,000/μL. JAK2 V617F mutation is positive. LDH is mildly elevated, no blast cells on smear. Bone marrow shows hypercellularity with megakaryocyte clustering. Which myeloproliferative neoplasm does this best represent?
- A Primary myelofibrosis ✓
- B Polycythemia vera
- C Essential thrombocythemia
- D Chronic myeloid leukemia
Correct answer: A. Primary myelofibrosis
Explanation
Primary myelofibrosis (PMF) presents with splenomegaly, constitutional symptoms, anemia, and leukocytosis; leukoerythroblastosis (tear-drop cells, nucleated RBCs, left-shifted WBCs) is characteristic. Bone marrow shows fibrosis and clustering of atypical megakaryocytes. JAK2 V617F is positive in ~50% of PMF. Polycythemia vera features erythrocytosis as the hallmark. Essential thrombocythemia predominates with thrombocytosis and minimal splenomegaly. CML has BCR-ABL translocation without JAK2 mutation.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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