CT confirmed total collapse secondary to a T4N3M1 lung tumor.

White-out of the hemithorax on CXR has a limited number of causes. The differential diagnosis can be shortened further with one simple observation - the position of the trachea. Is it central, pulled or pushed from the side of opacification?

• pulled: pneumonectomy, total lung collapse, pulmonary agenesis
• central: consolidation, mesothelioma
• pushed: pleural effusion, diaphragmatic hernia

Case credit: Dr Ian Bickle