Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The hilar and mediastinal contours are normal . There are subtle opacities at the lung bases bilaterally . There is no evidence of pleural effusion or pneumothorax . The visualized osseous structures are unremarkable . Note is made of a granuloma or a rib bone island overalying the anterior 1st rib .
    OUTPUT:
    
Subtle opacities at the lung bases bilaterally may be secondary to pneumonia .