Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is an equivocal retrocardiac opacity . This could represent pneumonia in the right clinical setting , or may be a prominent bronchovascular bundle or atelectasis . The lungs are otherwise clear . The cardiomediastinal silhouette is unremarkable . There is no pneumothorax or pleural effusion . The osseous structures are unremarkable .
    OUTPUT:
    
Equivocal retrocardiac opacity , which could represent pneumonia in the right clinical setting or which may be a prominent bronchovascular markings or atelectasis . Otherwise unremarkable chest radiographs .