Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a subtle opacity overlying the mid left lung field , which appears new compared to the prior exam . Right central venous stent is again seen in place . Both lungs demonstrate relatively extensive perihilar areas of atelectasis . There is no large pleural effusion or pneumothorax . The heart size is normal .
    OUTPUT:
    
Subtle increase in opacity overlying the mid left lung field is concerning for pneumonia .