A 62-year-old man has a refractory anemia with high serum iron, high transferrin saturation, and elevated ferritin. Bone marrow aspirate stained with Prussian blue shows erythroid precursors with a perinuclear ring of blue granules. This finding represents iron accumulation in which intracellular location?
- A Lysosomes of macrophages
- B Mitochondria of erythroid precursors ✓
- C Nucleus of erythroid precursors
- D Endoplasmic reticulum of plasma cells
Correct answer: B. Mitochondria of erythroid precursors
Explanation
Ring sideroblasts are the hallmark of sideroblastic anemia. Iron accumulates in the mitochondria of erythroid precursors because heme synthesis is defective, classically due to impaired delta-ALA synthase function or its cofactor pyridoxine. On Prussian blue stain these mitochondrial deposits form a perinuclear ring. Macrophage iron appears as diffuse hemosiderin rather than rings, and iron does not accumulate in nuclei or plasma cell endoplasmic reticulum.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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