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.