Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a mild ill - defined densities in the left lower lobe that could be atelectasis or a mild pleural effusion . No edema , no pneumothorax . The mediastinal and cardiac contour are normal .
    OUTPUT:
    
Mild densities in the left lower lobe probably secondary to atelectasis or pleural effusion .