Pulmonary interstitium is a collection of support tissues within the lung that includes the alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues.
The pulmonary interstitium can be divided into three zones - axial, parenchymal and peripheral .
In interstitial lung disease, some diseases affect all zones while others have a predilection to affect a particular pulmonary interstitial zone :
- axial: surrounding the bronchovascular tree
- parenchymal: surrounding the pulmonary parenchyma
- peripheral: adjacent to the pleura