Spontaneous multiloculated multiseptated pneumomediastinum in a newborn baby: the spinnaker sail is rigged-CT features with pathologic correlation.

The CT appearance of a pathologically proven spontaneous multiloculated multiseptated pneumomediastinum in a newborn baby has not been reported in the English literature. Our baby was delivered vaginally at term and developed mild respiratory distress after birth. The antenatal history was unremarkable apart from borderline oligohydramnios. The multiple septa seen within the pneumomediastinum on CT on day 3 may simulate an underlying 'bubbly' lung lesion like congenital cystadenomatoid malformation or congenital lobar emphysema, but actually represent anatomically known fascia surrounding the thymus. Furthermore, in neonates, air in the mediastinum often loculates locally and tends not to dissect widely as in adults.