Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Most evident on the lateral view is a hazy opacity seen in the retrocardiac space , which was not as evident on prior film . While this may represent atelectasis , pneumonia in the appropriate clinical setting should not be excluded . There is no pneumothorax or pleural effusion . The mediastinal and cardiac silhouette are unremarkable .
    OUTPUT:
    
Hazy opacity , best appreciated on the lateral view , may represent atelectasis , although pneumonia should not be excluded in the appropriate clinical setting .