Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette is mildly enlarged . Lung volumes are low . The pulmonary vasculature is unremarkable . There is no pleural effusion or pneumothorax . A possible retrocardiac opacity is noted , which in the appropriate clinical context , may represent pneumonia .
    OUTPUT:
    
Possible left lower lobe pneumonia in the appropriate clinical context .