Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs were provided . There is an ill - defined subtle retrocardiac opacity projecting over the lower spine concerning for infection . Dense ill - defined material projecting over the mediastinum may be external to the patient as it is not localized on the lateral view . There is no pleural effusion or pneumothorax . Heart size is mildly enlarged . The bones are intact . The imaged upper abdomen is unremarkable .
    OUTPUT:
    
Subtle retrocardiac opacity may represent infection in the correct clinical setting .