Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided demonstrate a large retrocardiac density , stable , compatible with known hiatal hernia . The lungs are clear . No signs of pneumonia or CHF . No pleural effusion or pneumothorax . The heart is unchanged in overall contour and size . The mediastinal contour is normal . Tracheobronchial tree calcification noted . Bony structures are intact .
    OUTPUT:
    
No acute findings . Large hiatal hernia redemonstrated .