Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a rounded left lower lobe retrocardiac opacity which is not significantly changed in size from the most recent CT of the chest in ___ . The lungs are otherwise clear . There is no pulmonary edema , pleural effusion , or pneumothorax . The cardiomediastinal silhouette is normal .
    OUTPUT:
    
Retrocardiac opacity , not significantly changed since the prior CT of the chest in ___ , and likely due to superinfection of pulmonary sequestration . Results were discussed with Dr . ___ ___ room resident ) at 5 :45 a .m . on ___ via telephone by Dr . ___ at the time the findings were discovered .