Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal silhouette is unchanged since the prior examination . A left - sided pacemaker device is again seen with leads terminating in the right atrium and right ventricle . Mitral annular calcifications are again noted . The aorta is diffusely calcified . Diffuse interstitial opacities have progressed since ___ . A small left pleural effusion may be present . The opacity in the retrocardiac region though not correspond to specific findings on the frontal radiograph , but in the appropriate clinical context , may represent pneumonia .
    OUTPUT:
    
Posterior opacity possibly representing pneumonia in the appropriate clinical context .