A 75-year-old man has anemia, fatigue, and recurrent infections. Bone marrow shows hypercellular marrow with dysplastic changes in all three cell lines: hypogranular neutrophils with pseudo-Pelger-Huet anomaly, ringed sideroblasts (>15%), and megakaryocytes with hypolobated nuclei. Blasts are 4%. Cytogenetics shows deletion 5q. The diagnosis is:
- A Aplastic anemia
- B Acute myeloid leukemia (AML)
- C Myelodysplastic syndrome (MDS) ✓
- D Reactive dysplasia from B12 deficiency
Explanation
Myelodysplastic syndrome (MDS) is a clonal stem cell disorder characterized by ineffective hematopoiesis with morphological dysplasia in ≥10% of cells in one or more myeloid lineages, cytopenias, and <20% blasts (20% or more would be AML). Ringed sideroblasts (iron-loaded mitochondria around the nucleus), pseudo-Pelger-Huet neutrophils, and hypolobated megakaryocytes are classic dysplastic features. Del(5q) is the most favorable isolated cytogenetic abnormality in MDS and responds to lenalidomide. Aplastic anemia shows hypocellular marrow; B12 deficiency causes macrocytic dysplasia but no clonal cytogenetic abnormalities.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.