Spontaneous pneumomediastinum is not uncommon in neonates [1]. Most cases are clinically insignificant; however it may be the first indicator of pulmonary interstitial emphysema [2].
        Radiographically, pneumomediastinum appears as a radiolucency outlining the heart and mediastinum on AP films. The thymus is frequently elevated by air, producing the "angle wings" or "spinnaker sail" sign (Figure 1).There may be a continuous diaphragm sign caused by air in the mediastinum beneath the heart.
        Althoug it can be difficult to distinguish pneumomediastinum from pneumopericardium or a medial  pneumothorax, pneumopericardium does not extend beyond the origins of the aorta and the pulmonary artery, and pneumopericardium and medial pneumothorax do not elevate or outline the thymus [1].