Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear without focal consolidation . No pleural effusion or pneumothorax is seen . Large relatively rounded retrocardiac opacity , best seen on the frontal view with suggestion of central lucency , may be due to a large hiatal hernia . The cardiac silhouette is top - normal . Mediastinal contours are unremarkable .
    OUTPUT:
    
Top - normal cardiac silhouette size . No pulmonary edema , focal consolidation , or pleural effusions seen . Large rounded retrocardiac density with central lucency may represent a large hiatal hernia .