Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral views of the chest were provided . There is a large retrocardiac density containing an air - fluid level compatible with hiatal hernia . The heart does appear to be mildly enlarged , though difficult to assess on the lateral view given the presence of the hiatal hernia . No signs of pneumonia , aspiration , CHF , effusion , or pneumothorax . Mediastinal contour is normal . Bony structures are intact . No free air below the right hemidiaphragm .
    OUTPUT:
    
Large hiatal hernia . Mild cardiomegaly .