Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is increased retrocardiac opacity which projects over the spine on the lateral view , findings which may reflect atelectasis or early pneumonia . The remainder of the lungs are clear . There is no pulmonary edema or pleural effusions . Cardiomediastinal and hilar contours are within normal limits . There is no pneumothorax .
    OUTPUT:
    
Retrocardiac opacity may reflect atelectasis or early pneumonia in the appropriate clinical setting .