Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest . There is focal silhouetting of the descending thoracic aorta in the retrocardiac region with time subtle increased opacity in the infrahilar region . On the lateral view . . Elsewhere , the lungs are clear . There is no effusion . The cardiomediastinal silhouette is normal . Osseous structures are unremarkable .
    OUTPUT:
    
Focal silhouetting of the descending thoracic aorta with subtle increased retrocardiac opacity could represent focal infection in the proper clinical setting .