Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is likely within normal limits , although the left contour is somewhat obscured by a large retrocardiac rounded mass with lucency within it , most compatible with a large hiatal hernia . The mediastinal contours are within normal limits . The lungs are otherwise clear . There is no pleural effusion or pneumothorax . There is no subdiaphragmatic free air . Clips in the right upper quadrant of the abdomen are compatible with prior cholecystectomy .
    OUTPUT:
    
Large hiatal hernia , but no acute cardiopulmonary process and no subdiaphragmatic free air .