Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest . AP projection and low lung volumes exaggerate heart size , which is top normal . Upper mediastinal contours are stable . Small opacity in the right lung base projects over the lower thoracic spine . No pleural effusion or pneumothorax .
    OUTPUT:
    
Focal right lower lobe opacity may represent pneumonia , aspiration , or atelectasis . Short interval follow - up CXR may be helpful .