Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a retrocardiac opacity which likely represents left lower lobe pneumonia . There is atelectasis in the right middle lobe . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are unremarkable .
    OUTPUT:
    
Left lower lobe pneumonia . Right middle lobe atelectasis .