A 66-year-old man presents with progressive abdominal distension and early satiety. The spleen extends 12 cm below the costal margin. Hemoglobin is 8.9 g/dL, WBC 7,500/µL, platelets 140,000/µL. Peripheral smear shows frequent teardrop-shaped red cells and occasional nucleated precursors of all three lineages. Bone marrow aspiration yields no material, and trephine biopsy shows a hypercellular marrow replaced by fibrosis with atypical megakaryocyte clusters. What is the most likely diagnosis?
- A Hairy cell leukemia
- B Chronic myeloid leukemia
- C Primary myelofibrosis ✓
- D Polycythemia vera, spent phase
Correct answer: C. Primary myelofibrosis
Explanation
Massive splenomegaly from extramedullary hematopoiesis, leukoerythroblastosis with teardrop cells, a dry tap on aspiration, and marrow fibrosis with atypical megakaryocytes form the classic tetrad of primary myelofibrosis, a Philadelphia-negative myeloproliferative neoplasm often driven by JAK2, CALR, or MPL mutations. CML shows granulocytic hyperplasia with basophilia rather than a fibrotic dry tap, and hairy cell leukemia features TRAP-positive B cells. Spent-phase polycythemia vera requires documented prior erythrocytosis.
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.