Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle patchy left base retrocardiac opacity seen on the frontal view , not substantiated on lateral view , may be due to atelectasis , however consolidation due to infection or aspiration is not excluded in the appropriate clinical setting . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are stable . There are degenerative changes are seen along the spine and at the right acromioclavicular joint .
    OUTPUT:
    
Subtle left base retrocardiac patchy opacity seen on the frontal view , not substantiated on the lateral view , may be due to atelectasis although consolidation from infection or aspiration not excluded in the appropriate clinical setting .