Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . There is a moderate left pleural effusion with left retrocardiac consolidation , which may reflect atelectasis . Underlying consolidation is not excluded . There is no right pleural effusion . There is no pneumothorax . Right basilar atelectasis is present . Small left humeral enchondroma is noted .
    OUTPUT:
    
Moderate left pleural effusion with left retrocardiac opacity , which may reflect atelectasis . Underlying pneumonia not excluded .