MASSIVE collapse of the lung is a condition in which one or more lobes, previously well aerated, lose their air content and collapse. It has been well defined by John Rose Bradford (7) as “an unusual condition in which the lung, without the presence of any gross lesion, such as bronchial obstruction, pleural effusion, etc., interfering with the free entry of air, becomes airless to a greater or less degree.” In its collapsed state the lung occupies a smaller space than it did when fully expanded, and becomes denser in character. The condition is not associated with pneumothorax, nor is there any separation of the lung from the chest wall. To compensate for the space lost from collapse of the lung, the chest wall is depressed, the heart and mediastinal structures are drawn over toward the involved side, and the diaphragm is pulled upward. When one considers the small size to which a normal lung may collapse in the presence of pneumothorax and its relative radiolucency when fully collapsed, it is surprising...