Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours appear stable . There is no pleural effusion or pneumothorax . There is vague opacity at the left lung base but very similar to prior findings .
    OUTPUT:
    
Vague opacity obscuring the left cardiac border ; given chronicity this may be due to minor chronic scarring , although a recurrent infectious process is not excluded .