Pleural Effusion

An abnormal chest x-ray shows a large volume of fluid (arrows) inside the pleural sac surrounding one lung. In this case, this finding is related to a pneumonia caused by Hemophilus influenzae. A normal chest x-ray is shown on the right for comparison; the heart (H), lungs (L), vertebrae (v), and collarbone (C) can be seen.

(Left: AP Fishman, Fishman's Pulmonary Diseases and Disorders, 3 ed, 1998, McGraw-Hill, Fig. 88-5e; right: MY Chen, Basic Radiology, 1996, McGraw-Hill, Fig. 4-1b; with permission.)