Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well inflated . The right lung is clear while the left lung demonstrates a retrocardiac opacity that is confirmed in the lateral view . The cardiomediastinal and hilar contours are unremarkable . There is no evidence of pleural effusion or pneumothorax .
    OUTPUT:
    
Retrocardiac opacity might represent atelectasis versus consolidation secondary to infectious / inflammatory process .