A 20-year-old man presents with progressive fatigue, pallor, and recurrent infections for 2 months. CBC shows pancytopenia: Hb 6.8 g/dL, WBC 1.8 × 10⁹/L, platelets 18 × 10⁹/L. Reticulocyte count is 0.4%. Bone marrow biopsy shows hypocellularity with fatty replacement and absence of megakaryocytes. What is the most likely diagnosis?

• A Megaloblastic anemia
• B Paroxysmal nocturnal hemoglobinuria
• C Myelodysplastic syndrome
• D Aplastic anemia ✓

Explanation

Pancytopenia with reticulocytopenia and bone marrow hypocellularity with fatty replacement is the hallmark of aplastic anemia. PNH and MDS can present similarly but PNH shows GPI-anchor deficient clones and MDS shows dysplasia and often hypercellular marrow. Megaloblastic anemia typically shows hypersegmented neutrophils and megaloblastic marrow, not hypocellularity.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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