A 42-year-old man with iron deficiency anemia secondary to chronic GI blood loss undergoes bone marrow examination. Which morphologic finding on bone marrow aspirate best distinguishes iron deficiency anemia from anemia of chronic disease?

Question

Accepted Answer

A. Absent or markedly reduced iron stores (Prussian blue stain negative). ## Bone Marrow Iron Stores: The Discriminator

### Pathophysiologic Basis

**Key Point:** Iron stores in bone marrow macrophages (assessed by Prussian blue staining) are the single best morphologic discriminator between IDA and anemia of chronic disease (ACD). IDA shows absent/depleted stores; ACD shows normal or increased stores with impaired utilization.

### Bone Marrow Findings Comparison Table

| Finding | Iron Deficiency Anemia | Anemia of Chronic Disease |
| --- | --- | --- |
| **Iron Stores (Prussian Blue)** | Absent or markedly reduced | Normal or increased |
| **Sideroblasts** | Absent or rare | Reduced (impaired utilization) |
| **Marrow Cellularity** | Hypercellular (erythroid hyperplasia) | Normocellular or hypocellular |
| **Erythroid Precursors** | Increased (response to anemia) | Normal or decreased |
| **Hemosiderin in Macrophages** | None | Present |
| **Pathophysiology** | Depleted iron stores | Iron sequestered; hepcidin ↑ |

### Why Prussian Blue Stain is Diagnostic

**High-Yield:** Prussian blue staining detects hemosiderin (storage iron) in bone marrow macrophages:
- **IDA:** No blue granules = absent iron stores (the hallmark of iron deficiency)
- **ACD:** Blue granules present = normal/increased iron stores, but hepcidin-mediated block prevents iron utilization

**Clinical Pearl:** This distinction is critical because IDA requires iron supplementation, while ACD does not. Giving iron to an ACD patient is futile and may cause harm (iron overload).

### Why Other Options Are Shared Features

Hypercellular marrow with erythroid hyperplasia, microcytic hypochromic normoblasts, and reduced sideroblasts can occur in both conditions as responses to anemia or iron unavailability. Only the **absence of iron stores** is pathognomonic for IDA.

[cite:Robbins 10e Ch 14]

Answer

B. Microcytic hypochromic normoblasts

Answer

C. Increased iron in macrophages with reduced sideroblasts

Answer

D. Hypercellular marrow with erythroid hyperplasia

A 42-year-old man with iron deficiency anemia secondary to chronic GI blood loss undergoes bone marrow examination. Which morphologic finding on bone marrow aspirate best distinguishes iron deficiency anemia from anemia of chronic disease?

Explanation

Bone Marrow Iron Stores: The Discriminator

Pathophysiologic Basis

Bone Marrow Findings Comparison Table

Why Prussian Blue Stain is Diagnostic

Why Other Options Are Shared Features

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Finding	Iron Deficiency Anemia	Anemia of Chronic Disease
Iron Stores (Prussian Blue)	Absent or markedly reduced	Normal or increased
Sideroblasts	Absent or rare	Reduced (impaired utilization)
Marrow Cellularity	Hypercellular (erythroid hyperplasia)	Normocellular or hypocellular
Erythroid Precursors	Increased (response to anemia)	Normal or decreased
Hemosiderin in Macrophages	None	Present
Pathophysiology	Depleted iron stores	Iron sequestered; hepcidin ↑