Spontaneous pulmonary interstitial emphysema in a term unventilated infant.

Pulmonary interstitial emphysema (PIE) is a form of air block most frequently seen in ventilated preterm infants with severe lung disease; it is rarely reported in spontaneously breathing term infants. We report on an infant previously diagnosed with laryngomalacia and congestive heart failure and with evidence of antenatal stroke before the onset of pulmonary disease. He presented at 6 weeks of age with spontaneous pneumothorax. Focal cystic changes were seen on imaging studies of the lungs. There was no prior history of mechanical ventilation. Prior chest X-rays did not show cystic changes. He subsequently underwent resection of the affected lung areas. Pathologic examination revealed persistent PIE with cystic expansion, pleural blebs, and reactive pleuritis, as well as subpleural air-space enlargement. The patient did well postoperatively and was discharged home without further problems. This case demonstrates that PIE can occur in an infant without any history of mechanical ventilation, suggesting the need for a high index of suspicion for PIE, even in nonventilated and spontaneously breathing term neonates. PIE should be included in the differential diagnosis of cystic lung lesions in all young infants.