Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle opacification within the retrosternal clear space on the lateral , which may represent a subtle pneumonia . Linear opacities at the left lung base likely reflect atelectasis . No additional focal consolidations . No pulmonary edema . Normal appearance of the cardiomediastinal silhouette . No pneumothorax . No pleural effusion .
    OUTPUT:
    
Subtle opacification within the retrosternal clear space on the lateral , which may represent a subtle pneumonia .