Obtunded toddler who was being carried down stairs by an adult who fell on top of them

CXR and CT of pneumomediastinum
CXR AP shows air outlining the thymus (thymic sail sign) and that the diaphragm can be traced throughout its course (continuous diagphragm sign). Axial CT with contrast of the chest shows air in the posterior mediastinum in front of the spine.

The diagnosis was pneumomediastinum.