Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest are provided . There is subtle minimal opacity in the left lower lobe , retrocardiac region , which could represent a very early pneumonia . Otherwise , the lungs are clear . Heart and mediastinal contours are normal . No pleural effusion or pneumothorax . Bony structures are intact .
    OUTPUT:
    
Possible early opacity in the left lower lobe could represent pneumonia .