Kerley Lines

We often read and hear about kerley lines on chest X-Ray. But what are they and what do they mean?

Here is a AP chest X-Ray film. Note the arrows and arrowheads:

Kerley's A lines (Arrows): Linear opacities extending from the periphery to the hila. They are caused by distension of anastomotic channels between peripheral and central lymphatics

Kerley's B lines (white arrowheads): Short horizontal lines situated perpendicularly to the pleural surface at the lung base. They represent edema of the interlobular septa.

Kerley's C lines (black arrowheads): Reticular opacities at the lung base. They represent Kerley's B lines en face.

All of these radiologic signs suggest cardiogenic pulmonary edema.