Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were performed . The left posterior sulcus , as seen on the lateral view , is blunted , due to either a small effusion or pleural scarring . Atelectasis is seen at the left lung base , best appreciated on the lateral view . The cardiac and mediastinal contours are normal . The hilar and pleural structures are unremarkable . There are no acute osseous abnormalities appreciated .
    OUTPUT:
    
Left basilar atelectasis . Very small left pleural effusion or scarring .