Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is dense retrocardiac opacity silhouetting the descending thoracic aorta and medial hemidiaphragm compatible with a left lower lobe consolidation . Elsewhere , the lungs are clear . The cardiomediastinal silhouette is within normal limits . Osseous and soft tissue structures are unremarkable .
    OUTPUT:
    
Left lower lobe consolidation compatible with pneumonia . Recommend repeat after treatment to document resolution .