Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: One portable upright AP view of the chest . Right PICC line ends at the cavoatrial junction . Sternotomy wires and mitral valve hardware is seen . The right lung is clear . There is increased opacity at the left lung base , likely representing effusion with associated atelectasis . No pneumothorax .
    OUTPUT:
    
Likely left pleural effusion with associated atelectasis but can not rule out pneumonia .