History: 60 year old male with lower extremity edema and shortness of breath.
This is an excellent example of Kerley B lines. These lines are created by interlobular septal thickening, typically created by fluid collecting within the pulmonary interstitium. Classically Kerley B lines are seen with cardiogenic pulmonary edema, where left ventricular failure causes increased intravascular hydrostatic pressure at the level of the pulmonary capillaries. Interstitial pulmonary edema has multiple other causes.
Interlobular septal thickening can be seen with other disease entities, including lymphangitic carcinomatosis, sarcoidosis, pulmonary alveolar proteinosis, and usual interstitial pneumonia.