Presentation
Born at 32/40. Required 2 days of CPAP. Never intubated.. Stepped down on day 3. Readmitted to NNU with progressive increase in work of breathing.
Patient Data

Minor increased opacification in mid and lower zones on the left. Otherwise, the lungs are clear. No effusion. No pneumothorax. Normal cardiomediastinal contour.

The left lung is hyperexpanded with multiple cyst-like lucencies throughout the hemithorax. Mediastinal shift to the right. The right lung is compressed because of mediastinal shift. The diaphragm is intact.
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The CT confirms the expansion of the left lung by cyst-like lucencies. The bronchovascular bundle traverses the cysts rather than being between them. Features here are of gas within the bronchial interstitium and pulmonary interstitial emphysema.
Case Discussion
Features here are most in keeping with pulmonary interstitial emphysema. Other differentials include:
- congenital lobar overinflation - but there are cyst-like lucencies on the plain film and no overinflated segment
- congenital pulmonary airway malformation - cyst-like lucencies, but the bronchovascular bundle runs down the center of the air-filled spaces, not between them
- congenital diaphragmatic hernia - definitely not with the intact diaphragm
The lobe was removed and the pathologist confirmed persistent pulmonary interstitial emphysema.
PIE in the neonatal setting is usually seen in premature infants who have been ventilated. Their stiff lungs (in the setting of RDS) predispose them to alveolar or interstitial rupture leading to dissection of gas along the bronchial interstitium.
This case highlights that PIE can occur unilaterally and asymmetrically, and does not only occur in a preterm ventilated neonate.