Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a large left pleural effusion . The right lung is clear . The cardiomediastinal silhouette is obscured . No pneumothorax is identified . Atherosclerotic calcifications of the aortic arch are noted .
    OUTPUT:
    
Large left pleural effusion with likely atelectasis of the underline left lower lobe .