Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A small linear opacity at the left base is more prominent than in the prior exam . There is no pulmonary edema , pleural effusion , or pneumothorax . The cardiomediastinal silhouette is normal .
    OUTPUT:
    
Small left basilar opacity , which given the size , is likely atelectasis . An early pneumonia can not be completely excluded in the proper clinical setting .