Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: On lateral view , there is subtle opacity at a posterior lung base , possibly left lower lobe on the frontal view . No additional focal consolidation is seen . No pleural effusion or pneumothorax is seen . The cardiac silhouette is top - normal . Mediastinal contours are unremarkable .
    OUTPUT:
    
Subtle patchy left lower lobe opacity could be due to infection or aspiration .