Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are within normal limits . Pulmonary vasculature is not engorged . Patchy retrocardiac opacities concerning for left lower lobe pneumonia . Right lung is clear . No pleural effusion or pneumothorax is present . Clips are seen in the right upper quadrant of the abdomen likely denoting prior cholecystectomy .
    OUTPUT:
    
Retrocardiac opacity concerning for left lower lobe pneumonia . Followup radiographs after treatment are recommended to ensure resolution of this finding .