Kerley B lines are 1 – 2 cm thin lines in the peripheries of the lung. They are perpendicular to, and extend out to the pleural surface. They represent thickened subpleural interlobular septa and are usually seen at the lung bases.
Causes of Kerley B lines include; pulmonary edema, lymphangitis carcinomatosa and malignant lymphoma, viral and mycoplasmal pneumonia, interstital pulmonary fibrosis, pneumoconiosis, sarcoidosis. They can be an evanescent sign on the CXR of a patient in and out of heart failure.
A repeat CXR the next day reveals a decrease in heart size and resolution of the Kerley B lines.
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