Bone marrow examination of a 60-year-old man with refractory anemia shows erythroid hyperplasia with numerous ring sideroblasts. The iron accumulation defining these cells occurs in which cellular compartment?

• A Mitochondria ✓
• B Golgi apparatus
• C Nucleus
• D Lysosomes

Explanation

Ring sideroblasts are erythroid precursors with iron-loaded mitochondria arranged in a perinuclear ring, visible as Prussian blue positive granules encircling at least one third of the nucleus. The defect lies in mitochondrial heme synthesis, classically impaired delta-aminolevulinic acid synthase function or other steps of the pathway, so iron cannot be incorporated into protoporphyrin and accumulates in mitochondria. Nuclear, Golgi, and lysosomal iron deposition does not define this finding.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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