Fluid accumulation in preexisting pulmonary air spaces.

Four patients with fluid accumulation in preexisting pulmonary air spaces are presented. Three patients developed fluid in an infected bulla; the fourth patient bled into a bulla. The slow spontaneous resolution of the accumulated fluid and the success of a conservative therapeutic approach are emphasized. The characteristic radiologic features of fluid-filled intrapulmonary air spaces are described and criteria for the differentiation from lung abscesses and empyemas are outlined.