Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Two views were obtained of the chest . While no discrete abnormality is seen on the frontal view , there is a vague retrocardiac opacity . On the lateral mild increase in opacification of the posterior lower lungs suggests left lower lobe pneumonia . There is no pleural effusion or pneumothorax . The heart is top - normal in size with normal mediastinal and hilar contours .
    OUTPUT:
    
Vague opacity on the lateral view could reflect left lower lobe pneumonia .