Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Chest PA and lateral radiograph demonstrates unremarkable mediastinal , hilar and cardiac contours . The lungs are clear . Minimal blunting of the left costophrenic angle may indicate small left pleural effusion . No pneumothorax evident .
    OUTPUT:
    
Normal mediastinal contour . Possible small left pleural effusion .