Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are moderately well expanded . An opacity in the left lung base is probably pneumonia . The lungs are otherwise clear . Pleural thickening is noted on the right . There is no pleural effusion or pneumothorax . The cardiomediastinal silhouette is unremarkable . Old rib fractures are seen on the right in various stages of healing .
    OUTPUT:
    
Left lung base opacity , which may represent pneumonia .