Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . There is a retrocardiac opacity which is posterior in position on the lateral view compatible with left lower lobe pneumonia . The right lung is clear . No pleural effusions . Cardiomediastinal silhouette normal . Bony structures intact .
    OUTPUT:
    
Left lower lobe pneumonia .