Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . There is persistent vague opacity in the lingula but this seems to be a background finding of long chronicity that may indicate minor atelectasis or scarring . The chest is hyperinflated . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Waxing and waning minor lingular opacity suggesting atelectasis or scarring ; pneumonia seems less likely to explain this appearance .