Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded . A dense retrocardiac opacity is present , which is confirmed with a prominent spine sign in the lateral view . Otherwise , no other focal opacities are identified . There might be small bilateral pleural effusions . There is no pneumothorax . Cardiomediastinal and hilar contours are unremarkable .
    OUTPUT:
    
Left lower lobe pneumonia . Repeat after treatment to document resolution . These findings were communicated to Dr ___ by Dr ___ on ___ at 10 am immediately after discovery of the findings via phone .