Hemithorax white-out (differential)

Complete white-out of a hemithorax on the chest x-ray 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? Is there pulmonary volume loss or volume gain? Is there rib crowding? Is the heart pushed or pulled?

Trachea pulled toward the opacified side

• pneumonectomy
• total lung collapse: e.g. endobronchial intubation
• pulmonary agenesis
• pulmonary hypoplasia

Trachea remains central in position

• consolidation
• pulmonary edema/ARDS
• pleural mass: e.g. mesothelioma
• chest wall mass: e.g. Askin/Ewing sarcoma
• being on extracorporeal membrane oxygenation (ECMO) ^4,5

Pushed away from the opacified side

• pleural effusion
• diaphragmatic hernia
• large pulmonary mass
• diaphragmatic rupture

See also

• air space opacification
• air bronchogram