Neonatal pneumomediastinum and the spinnaker-sail sign

Abstract

A male infant was born at 40 weeks of gestation by vacuum-assisted vaginal delivery. Mild respiratory distress with expiratory grunting and subcostal retraction was noted 1 hour after birth. Arterial oxygen saturation remained at more than 95% without the administration of supplemental oxygen. Chest radiography performed 6 hours after birth (Panel A) showed the spinnaker-sail sign, consisting of a large, wedge-shaped opacity extending from the right hemidiaphragm to the superior mediastinum (white arrows), representing thymic tissue displaced from its usual location by a collection of gas under pressure (black arrows). Axial computed tomography of the chest revealed air trapped between the pericardial sac and the thymus, confirming a diagnosis of anterior pneumomediastinum (Panel B, arrow). Named for its visual resemblance to the headsail of a boat, the spinnaker-sail sign occurs with a spontaneous anterior pneumomediastinum and usually resolves without specific treatment. After being observed for clinical and radiographic improvement for 3 weeks, the infant was discharged home in good condition.