Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Mild to moderate enlargement of the cardiac silhouette is unchanged . The mediastinal contour is similar . A moderate layering left pleural effusion likely accounts for the left perihilar haziness . Dense retrocardiac opacification could reflect compressive atelectasis though infection can not be excluded . Right lung is grossly clear without right - sided pleural effusion . No definite pulmonary edema is demonstrated . No pneumothorax is present . Multiple clips project over the epigastric region . Moderate multilevel degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Moderate layering left pleural effusion . Retrocardiac opacity may reflect compressive atelectasis but infection is not excluded .