Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size , mediastinal , and hilar contours are normal . There is a coalescent opacity behind the heart with obscuration of the left hemidiaphragm , indicating a left lower lobe pneumonia . Osseous structures are unremarkable .
    OUTPUT:
    
1 . Coalescent opacity and obscuration of the left hemidiaphragm indicates a left lower lobe pneumonia .