Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP and lateral views of the chest were provided . There is a retrocardiac density which is compatible with a known hiatal hernia . The lungs are clear without signs of pneumonia or CHF . Cardiomediastinal silhouette appears grossly stable . Bony structures are intact .
    OUTPUT:
    
Hiatal hernia . No signs of pneumonia .