Pathology.—Interstitial emphysema is characterized by air dissecting within the interstitium of the lung, typically in the peribronchovascular sheaths, interlobular septa, and visceral pleura. It is most commonly seen in neonates receiving mechanical ventilation.
Radiographs and CT scans.—Interstitial emphysema is rarely recognized radiographically in adults and is infrequently seen on CT scans (Fig 30). It appears as perivascular lucent or low-attenuating halos and small cysts. [Fleischner Society]