Radiologic distinction of pyogenic pulmonary infection from Pneumocystis carinii pneumonia in AIDS patients.

Thirty-four episodes of pyogenic pulmonary infection in 30 patients infected with human immunodeficiency virus (HIV) and 30 episodes of Pneumocystis carinii pneumonia (PCP) in 30 AIDS patients were reviewed to determine if the radiologic features were more helpful than clinical and laboratory findings in the differential diagnosis. The radiologic features of pyogenic pulmonary infection included lobar consolidation, nodules, infiltrates with pleural effusions, round infiltrates, and pleural effusions alone. These features are uncommon in PCP. The chest radiograph may be highly suggestive of a pyogenic process, especially when it shows local consolidation or nodules. Since bacterial pneumonias have a more favorable outcome, it is concluded that the radiologic features should be the primary guide to prompt diagnosis and treatment.