Interlobular septal thickening

What it means

Presence of thickening of the interlobular septa of the lungs as seen on a CT scan.

Interlobular septa are 10-20nm long structures at the border of the secondary pulmonary lobules and which are usually perpendicular to the pleura in the periphery of the lung. Interlobular septa are composed of connective tissue and contain pulmonary venules and lymphatics. Diseases that affect one of the components of the interlobular septa may lead to thickening of the septa, which makes the visible on computed tomography (CT) scans. Some of the diseases that may be associated with this phenotypic feature are pulmonary edema, pulmonary lymphangitis carcinomatosis, leukemic or lymphomic involvement of the lung, diffuse alveolar hemorrhage, Nieman-Pick disease, and pneumonia.

Rare diseases that can present with this4

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Interlobular lines (pulmonary CT finding) · Interlobular septal thickening on pulmonary HRCT · Peripheral lines (pulmonary CT finding) · Septal lines (pulmonary CT finding) · Septal thickening (pulmonary CT finding) · Short lines (pumonary CT finding)