Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral radiographs of the chest show mild opacity in the right lung base which could represent atelectasis or a developing infectious process . The rest of the lungs are clear although hyperexpanded indicative of emphysema . The hilar , mediastinal , and cardiac contours are normal . Slightly tortuous descending thoracic aorta is noted . No pleural effusion or pneumothorax .
    OUTPUT:
    
Opacity at the right lung base may represent atelectasis or early pneumonia in the appropriate clinical setting .