Learning Objective
Describe the types of infarcts (red and pale), the conditions under which they occur, and the underlying pathophysiology.
Types of Infarcts
Red (Hemorrhagic) Infarct
Red infarcts occur in tissues where blood can re-enter damaged areas. These typically involve: Venous occlusion
Example: ovarian or testicular torsion
Tissues with dual or extensive collateral blood supply
- Liver
- Lung
- Intestine
- Testes
Reperfusion injuries
- Example: restoration of blood flow after angioplasty
- Mechanism: reperfusion → ↑ free radical generation → additional cellular damage
Key Feature:
Tissue becomes hemorrhagic due to blood leakage into necrotic parenchyma.
Activity
Pale (Anemic) Infarct
Pale infarcts occur in solid organs supplied by a single end-arterial circulation with limited collateral flow.
Common sites:
- Heart
- Kidney
- Spleen
Key Feature:
The infarcted area is wedge-shaped and pale due to a lack of blood re-entry.
