Abnormal pulmonary thoracic imaging finding Continuous diaphragm sign 2019-01-06T10:59:57Z This sign is seen in pneumomediastinum in which air accumulates between the lower border of the heart and the superior part of the diaphragm, which results in complete visualization of the diaphragm in chest X-ray, hence named continuous diaphragm sign. Normally, the central part of the diaphragm is obscured by the heart, and hence is not seen on chest radiographs. Though this sign is commonly seen in pneumomediastinum, it can occasionally be also seen in pneumopericardium. This sign when seen, is a differential tool between pneumomediastinum and pneumothorax.