A 68-year-old man with newly diagnosed atrial fibrillation presents with acute left upper quadrant pain radiating to the left shoulder and low-grade fever. CT abdomen with IV contrast shows a non-enhancing, wedge-shaped pale lesion at the splenic periphery, with the base along the splenic capsule and apex directed toward the hilum, as marked **A** in the diagram. Which of the following best explains why the infarct marked **A** appears pale rather than hemorrhagic?

Question

Accepted Answer

C. The spleen has a single, end-arterial blood supply that does not permit dual inflow to flood the necrotic tissue, and dense splenic stroma resists secondary hemorrhage. ## Why option 1 is right

The spleen, like the kidney, has a single end-arterial circulation with no collateral blood supply. When a splenic arterial branch occludes, the tissue distal to the occlusion undergoes coagulative necrosis without hemorrhagic infiltration because the blocked artery cannot be supplemented by dual inflow (as occurs in organs with dual blood supply, e.g., lungs with pulmonary and bronchial circulation). Additionally, the dense fibrous stroma of the spleen mechanically resists secondary hemorrhage into the necrotic zone. This produces the characteristic pale or anemic infarct, not a hemorrhagic one. This is the classic morphological hallmark of end-arterial organs and is explicitly stated in Robbins Basic Pathology 11e as the reason splenic infarcts are pale rather than red.

## Why each distractor is wrong

- **Option 2**: Factually incorrect. The spleen does NOT have dual blood supply. It receives blood only from the splenic artery (a terminal branch of the celiac trunk); there is no secondary arterial source. This misunderstanding would lead to the wrong conclusion about infarct color.
- **Option 3**: Contradicts pathology. Splenic infarcts are pale from the outset due to the mechanism of end-arterial occlusion, not because they convert from hemorrhagic to pale over time. Hemorrhagic infarcts occur in organs with dual blood supply (e.g., lungs, intestine).
- **Option 4**: While organization does occur, it is not the reason for the pale appearance. The pale color is determined at the moment of infarction by the vascular anatomy and tissue properties, not by the speed of fibroblast infiltration.

**High-Yield:** End-arterial organs (spleen, kidney) → pale/anemic infarcts; dual-supply organs (lung, bowel) → red/hemorrhagic infarcts.

[cite: Robbins Basic Pathology 11e; UpToDate splenic infarction]

Answer

A. The spleen receives dual blood supply from the splenic artery and gastric artery, preventing hemorrhagic conversion

Answer

B. Splenic infarcts are always hemorrhagic initially but become pale within 24 hours due to fibrin deposition

Answer

D. The pale appearance is due to rapid organization of the infarct by fibroblasts, which occurs earlier in the spleen than in other organs

Explanation

Why option 1 is right

Why each distractor is wrong

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