Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal and hilar contours appear within normal limits . Seen on the frontal view only is equivocal increased opacity in the left mid lung , possibly a subtle lingular pneumonia or atelectasis . Elsewhere , the lungs appear clear . There are no pleural effusions or pneumothorax . Bony structures are unremarkable .
    OUTPUT:
    
Faint left mid lung opacity for which one could question subtle lingular pneumonia or possibly atelectasis .