Hepatization of lungs

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Hepatization of the lungs is an old term used to describe a severe pneumonia where the lung tissue becomes firm and looks like liver tissue. This happens when the air spaces inside the lungs fill with fluid, blood cells, and protein from the infection, so air can’t get through.

Cause
- The main cause is lobar pneumonia.

Imaging and signs
- On imaging, the affected area can look like a solid lump called a consolidation.
- In gross exam (like during autopsy), the lung may appear red, gray, or yellow depending on the stage.

Stages
- Red hepatization: The alveoli (air sacs) are filled with red blood cells, white blood cells, and fibrin. The lung tissue is red and firm and may sink in water.
- Gray hepatization: The red cells break down, leaving a gray, firmer exudate in the air spaces.
- Yellow hepatization: Rare today, seen occasionally after prolonged illness or at autopsy.

Progression
- Going from red to gray hepatization reflects the inflammation moving from an acute stage to a more organized, later stage. Yellow hepatization is unusual, often due to antibiotics.

Summary
- Hepatization describes a pneumonia stage where the lungs lose air and become solid enough to resemble liver tissue. It’s part of the old way doctors described lobar pneumonia.