Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Assessment of the cardiac silhouette size and mediastinal contours is difficult given the presence of a large left pleural effusion which causes mild rightward mediastinal shift . There is associated left basilar atelectasis . Apart from streaky right basilar atelectasis , the right lung is clear . No pulmonary edema or pneumothorax is present . There are multilevel mild degenerative changes seen in the thoracic spine .
    OUTPUT:
    
Large left pleural effusion with left basilar atelectasis .