Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest demonstrate hyperinflated lungs and flattening of hemidiaphragms . There is no focal consolidation or pleural effusion . There is no pulmonary edema . The hilar and mediastinal silhouettes are unremarkable . Heart size is top normal . Large retrocardiac opacity , likely represents the patient 's known hiatal hernia . There is relative paucity of gas within imaged upper abdomen . Visualized osseous structures appear intact .
    OUTPUT:
    
1 . Large retrocardiac opacity likely represents patient 's known hiatal hernia . 2 . Hyperexpanded lungs and flattened hemidiaphrags likely signify underlying emphysema .