Pulmonary cavitations appear roentgenographically as areas of rarefaction with diminished lung markings, usually bounded by annular shadows of increased density. If cavities are partially filled with fluid, air-fluid levels are present that shift with changes in position of the patient. In the early days of roentgenology it was believed that such areas were caused only by pulmonary destruction, and they were diagnosed as either pulmonary abscess or tuberculous cavitation.1 Later it was demonstrated that such shadows could also originate in the pleura and might represent the loculation of air, with or without fluid, in the pleural space.2 When large pulmonary cavities have been present in roentgenograms of young infants, congenital cysts of the lung have usually been invoked to explain their formation.3 More recently, substantial evidence has appeared which indicates that localized obstructive emphysema is an important factor in the production of cavernous lesions in the lungs.
CAFFEY J. REGIONAL OBSTRUCTIVE PULMONARY EMPHYSEMA IN INFANTS AND IN CHILDRENEMPHYSEMATOUS CAVITIES AND THEIR SIMILARITY TO NECROTIC CAVITIES, CONGENITAL PULMONARY CYSTS AND LOCULATED PNEUMOTHORAX. Am J Dis Child. 1940;60(3):586-605. doi:10.1001/archpedi.1940.02000030118011