Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs demonstrate left retrocardiac opacity . The heart size is top normal and the ascending aortic arch appears prominent . Right hilar prominence if of unclear significance given abscence of prior radiographs . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Left lower lobe pneumonia . Possible ascending aorta enlargement .