Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a retrocardiac opacity seen on the frontal view which is not confirmed on the lateral view . There are bilateral atelectatic changes . There is no pleural effusion or pneumothorax . The cardiac and mediastinal silhouettes are unremarkable .
    OUTPUT:
    
Possible retrocardiac opacity seen only on one view . In the appropriate clinical setting , left lower lobe pneumonia could be considered .