Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Right subclavian and left PICC are unchanged in position . Heart size is stable and retrocardiac opacification is unchanged . Opacification of the left lung base is concerning for a large pneumonia , although left lower lobe collapse from retained secretions is a possibility . Small left pleural effusion is likely . No pneumothorax .
    OUTPUT:
    
Persistent left lower lobe opacification , either from a large pneumonia or lobar collapse .