Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In comparison to the chest radiograph obtained 1 day prior , there is massive subcutaneous emphysema . While no pneumothorax definitively seen , the extensive subcutaneous emphysema might easily mask a pneumothorax , if present . There is extensive pneumomediastinum . The left lung is fully expanded and clear . No pleural effusions . Mild cardiomegaly is unchanged without pulmonary edema .
    OUTPUT:
    
While no pneumothorax is definitively seen , the new , extensive subcutaneous emphysema might easily mask a pneumothorax , if present . Extensive pneumomediastinum is also new since the immediate postoperative portable radiograph . These findings raise the possibility of a significant air leak .