Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal silhouette and pulmonary vasculature are unremarkable . On the frontal lobe is a retrocardiac opacity . There is no pneumothorax or pleural effusion .
    OUTPUT:
    
Vague retrocardiac opacity on frontal view which may represent a developing pneumonia in the appropriate clinical setting .