Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The patient is status post bilateral mastectomy . Since the prior examination , a right - sided breast drain has been placed and the previously seen air - fluid level in this location has resolved . A surgical device is seen within the left breast area . Opacities within the left lower lobe are seen . The right lung is clear . There is no pleural effusion or pneumothorax . The heart size is top normal . There are degenerative changes of the acromioclavicular and glenohumeral joints .
    OUTPUT:
    
Left lower lobe opacities likely are atelectasis but pneumonia or aspiration in the correct clinical setting can not be excluded .