Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest provided . Vague left lung base opacity may represent atelectasis . No convincing evidence for pneumonia . No effusion or pneumothorax . The cardiomediastinal silhouette is normal . Imaged osseous structures are intact . No free air below the right hemidiaphragm is seen .
    OUTPUT:
    
Mild left basal atelectasis . Otherwise normal