Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Equivocal retrocardiac opacity raises potential concern for a very mild pneumonia in the left lower lobe . Otherwise the lungs are clear . There is no pleural effusion , or pneumothorax . The cardiomediastinal silhouette is normal . Imaged osseous structures are intact . No free air below the right hemidiaphragm is seen .
    OUTPUT:
    
Subtle opacity in the left lower lobe raising potential concern for a mild pneumonia .