Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Retrocardiac opacity could represent pneumonia . A small left effusion difficult to exclude . Right lung is clear . Heart size is difficult to assess . Mediastinal contour is normal . Bony structures are intact .
    OUTPUT:
    
Left lower lobe opacity concerning for pneumonia with possible small effusion .