Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded . There is a retrocardiac opacity which can be confirmed with a spinal sign in the lateral view and is obscuring the posterior margin of the left hemidiaphragm . No other focal opacities are noted . Heart size can not be accurately assessed in this AP view , but the heart appears mildly enlarged . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Left lower lobe consolidation is most likely pneumonia .