Abstract
Spontaneous pneumomediastinum in the term newborn is relatively rare. We aim to emphasize the significance of Radiographic and CT features of spontaneous pneumomediastinum. We present an otherwise healthy 4-hour-old male, born by a caesarean section, presenting with sudden bulging of the left hemithorax and moderate respiratory distress. Chest radiography revealed an atypical unilateral lobular lucency distorting the mediastinum. CT scan showed an air collection with a multilobular upper border, containing thin straight and curvilinear septa. All segmental bronchi were identifiable. Limited scanning in decubitus position confirmed displacement of thymus and mediastinal air. Following conservative treatment, radiographic findings and symptoms resolved. Pneumomediastinum in neonates, unlike adults, loculates and does not dissect around broncho-vascular structures. Internal septa represent fascia surrounding the thymus. Thymic elevation and absence of lung abnormality constitute helpful imaging findings in support of spontaneous pneumomediastinum so that unnecessary and potentially harmful thoracotomy or chest tube placement are confidently avoided.